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Clarify what needs to be done to resolve the missing __noreturn warning.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/r/ab835a35d00bacf8aff0b56257df93f14fdd8224.1741975349.git.jpoimboe@kernel.org
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Make sure all fatal errors are funneled through the 'out' label with a
negative ret.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Link: https://lore.kernel.org/r/0f49d6a27a080b4012e84e6df1e23097f44cc082.1741975349.git.jpoimboe@kernel.org
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The CONFIG_X86_ESPFIX64 version of exc_double_fault() can return to its
caller, but the !CONFIG_X86_ESPFIX64 version never does. In the latter
case the compiler and/or objtool may consider it to be implicitly
noreturn.
However, due to the currently inflexible way objtool detects noreturns,
a function's noreturn status needs to be consistent across configs.
The current workaround for this issue is to suppress unreachable
warnings for exc_double_fault()'s callers. Unfortunately that can
result in ORC coverage gaps and potentially worse issues like inert
static calls and silently disabled CPU mitigations.
Instead, prevent exc_double_fault() from ever being implicitly marked
noreturn by forcing a return behind a never-taken conditional.
Until a more integrated noreturn detection method exists, this is likely
the least objectionable workaround.
Fixes: 55eeab2a8a11 ("objtool: Ignore exc_double_fault() __noreturn warnings")
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Brendan Jackman <jackmanb@google.com>
Link: https://lore.kernel.org/r/d1f4026f8dc35d0de6cc61f2684e0cb6484009d1.1741975349.git.jpoimboe@kernel.org
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Add a test to the guard region self tests to assert that the
/proc/$pid/pagemap information now made availabile to the user correctly
identifies and reports guard regions.
As a part of this change, update vm_util.h to add the new bit (note there
is no header file in the kernel where this is exposed, the user is
expected to provide their own mask) and utilise the helper functions there
for pagemap functionality.
[lorenzo.stoakes@oracle.com: fixup define name]
Link: https://lkml.kernel.org/r/32e83941-e6f5-42ee-9292-a44c16463cf1@lucifer.local
Link: https://lkml.kernel.org/r/164feb0a43ae72650e6b20c3910213f469566311.1740139449.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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It's not really possible to start diagnosing this without knowing the
actual error.
Also update the mlock2 helper to behave like libc would by setting errno
and returning -1.
Link: https://lkml.kernel.org/r/20250311-mm-selftests-v4-12-dec210a658f5@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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If running from a directory that can't be read by unprivileged users,
executing on-fault-test via the nobody user will fail.
The kselftest build does give the file the correct permissions, but after
being installed it might be in a directory without global execute
permissions.
Since the script can't safely fix that, just skip if it happens. Note
that the stderr of the `ls` command is unfiltered meaning the user sees a
"permission denied" error that can help inform them why the test was
skipped.
Link: https://lkml.kernel.org/r/20250311-mm-selftests-v4-11-dec210a658f5@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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This test allocates a page of every available size and doesn't have any
SKIP logic if the allocation fails. So, ensure it's available and skip
the test if we can't do so.
Link: https://lkml.kernel.org/r/20250311-mm-selftests-v4-10-dec210a658f5@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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This script must be run as root anyway (see all the writing to privileged
files in /proc etc).
Remove the unnecessary use of sudo to avoid breaking on single-user
systems that don't have sudo. This also avoids confusing readers.
Link: https://lkml.kernel.org/r/20250311-mm-selftests-v4-9-dec210a658f5@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Some filesystems don't support ftruncate()ing unlinked files. They return
ENOENT. In that case, skip the test.
Link: https://lkml.kernel.org/r/20250311-mm-selftests-v4-8-dec210a658f5@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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It seems that 9pfs does not allow truncating unlinked files, Mark Brown
has noted that NFS may also behave this way.
It doesn't seem quite right to call this a "bug" but it's probably a
special enough case that it makes sense for the test to just SKIP if it
happens.
Link: https://lkml.kernel.org/r/20250311-mm-selftests-v4-7-dec210a658f5@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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This calculation divides a fixed parameter by an environment-dependent
parameter i.e. the number of CPUs.
The simple way to avoid machine-specific failures here is to just put a
cap on the max value of the latter.
Link: https://lkml.kernel.org/r/20250311-mm-selftests-v4-6-dec210a658f5@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Suggested-by: Mateusz Guzik <mjguzik@gmail.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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So this can be debugged more easily.
Link: https://lkml.kernel.org/r/20250311-mm-selftests-v4-5-dec210a658f5@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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A later commit will bound this variable so it no longer necessarily
matches the number of CPUs. Rename it appropriately.
Link: https://lkml.kernel.org/r/20250311-mm-selftests-v4-4-dec210a658f5@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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It's obvious that this should fail in that case, but still, save the
reader the effort of figuring out that they've run into this by just
SKIPping
Link: https://lkml.kernel.org/r/20250311-mm-selftests-v4-3-dec210a658f5@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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It's pretty obvious that the test wouldn't work if you don't have the
feature enabled. But, it's still useful to SKIP instead of failing so the
reader can immediately tell that this is the reason why.
Link: https://lkml.kernel.org/r/20250311-mm-selftests-v4-2-dec210a658f5@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "selftests/mm: Some cleanups from trying to run them", v4.
I never had much luck running mm selftests so I spent a few hours digging
into why.
Looks like most of the reason is missing SKIP checks, so this series is
just adding a bunch of those that I found. I did not do anything like all
of them, just the ones I spotted in gup_longterm, gup_test, mmap,
userfaultfd and memfd_secret.
It's a bit unfortunate to have to skip those tests when ftruncate() fails,
but I don't have time to dig deep enough into it to actually make them
pass. I have observed the issue on 9pfs and heard rumours that NFS has a
similar problem.
I'm now able to run these test groups successfully:
- mmap
- gup_test
- compaction
- migration
- page_frag
- userfaultfd
- mlock
I've never gone past "Waiting for hugetlb memory to get depleted", in the
hugetlb tests. I don't know if they are stuck or if they would eventually
work if I was patient enough (testing on a 1G machine). I have not
investigated further.
I had some issues with mlock tests failing due to -ENOSRCH from mlock2(),
I can no longer reproduce that though, things work OK now.
Of the remaining tests there may be others that work fine, but there's no
convenient way to survey the whole output of run_vmtests.sh so I'm just
going test by test here.
In my spare moments I am slowly chipping away at a setup to run these
tests continuously in a reasonably hermetic QEMU environment via
virtme-ng:
https://github.com/bjackman/linux/blob/5fad4b9c592290f38e0f8bc73c9abb9c99d8787c/README.md
Hopefully that will eventually offer a way to provide a "canned"
environment where the tests are known to work, which can be fairly easily
reproduced by any developer.
This patch (of 12):
Just reporting failure doesn't tell you what went wrong. This can fail in
different ways so report errno to help the reader get started debugging.
Link: https://lkml.kernel.org/r/20250311-mm-selftests-v4-0-dec210a658f5@google.com
Link: https://lkml.kernel.org/r/20250311-mm-selftests-v4-1-dec210a658f5@google.com
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Fix misspelling flagged by codespell.
Link: https://lkml.kernel.org/r/20250215081803.1793-1-ujwal.kundur@gmail.com
Signed-off-by: Ujwal Kundur <ujwal.kundur@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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To enable SLAB_TYPESAFE_BY_RCU for vma cache we need to ensure that
object reuse before RCU grace period is over will be detected by
lock_vma_under_rcu().
Current checks are sufficient as long as vma is detached before it is
freed. The only place this is not currently happening is in exit_mmap().
Add the missing vma_mark_detached() in exit_mmap().
Another issue which might trick lock_vma_under_rcu() during vma reuse is
vm_area_dup(), which copies the entire content of the vma into a new one,
overriding new vma's vm_refcnt and temporarily making it appear as
attached. This might trick a racing lock_vma_under_rcu() to operate on a
reused vma if it found the vma before it got reused. To prevent this
situation, we should ensure that vm_refcnt stays at detached state (0)
when it is copied and advances to attached state only after it is added
into the vma tree. Introduce vm_area_init_from() which preserves new
vma's vm_refcnt and use it in vm_area_dup(). Since all vmas are in
detached state with no current readers when they are freed,
lock_vma_under_rcu() will not be able to take vm_refcnt after vma got
detached even if vma is reused. vma_mark_attached() in modified to
include a release fence to ensure all stores to the vma happen before
vm_refcnt gets initialized.
Finally, make vm_area_cachep SLAB_TYPESAFE_BY_RCU. This will facilitate
vm_area_struct reuse and will minimize the number of call_rcu() calls.
[surenb@google.com: remove atomic_set_release() usage in tools/]
Link: https://lkml.kernel.org/r/20250217054351.2973666-1-surenb@google.com
Link: https://lkml.kernel.org/r/20250213224655.1680278-18-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Shivank Garg <shivankg@amd.com>
Link: https://lkml.kernel.org/r/5e19ec93-8307-47c2-bb13-3ddf7150624e@amd.com
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Move several vma_area_struct members which are rarely or never used during
page fault handling into the last cacheline to better pack vm_area_struct.
As a result vm_area_struct will fit into 3 as opposed to 4 cachelines.
New typical vm_area_struct layout:
struct vm_area_struct {
union {
struct {
long unsigned int vm_start; /* 0 8 */
long unsigned int vm_end; /* 8 8 */
}; /* 0 16 */
freeptr_t vm_freeptr; /* 0 8 */
}; /* 0 16 */
struct mm_struct * vm_mm; /* 16 8 */
pgprot_t vm_page_prot; /* 24 8 */
union {
const vm_flags_t vm_flags; /* 32 8 */
vm_flags_t __vm_flags; /* 32 8 */
}; /* 32 8 */
unsigned int vm_lock_seq; /* 40 4 */
/* XXX 4 bytes hole, try to pack */
struct list_head anon_vma_chain; /* 48 16 */
/* --- cacheline 1 boundary (64 bytes) --- */
struct anon_vma * anon_vma; /* 64 8 */
const struct vm_operations_struct * vm_ops; /* 72 8 */
long unsigned int vm_pgoff; /* 80 8 */
struct file * vm_file; /* 88 8 */
void * vm_private_data; /* 96 8 */
atomic_long_t swap_readahead_info; /* 104 8 */
struct mempolicy * vm_policy; /* 112 8 */
struct vma_numab_state * numab_state; /* 120 8 */
/* --- cacheline 2 boundary (128 bytes) --- */
refcount_t vm_refcnt (__aligned__(64)); /* 128 4 */
/* XXX 4 bytes hole, try to pack */
struct {
struct rb_node rb (__aligned__(8)); /* 136 24 */
long unsigned int rb_subtree_last; /* 160 8 */
} __attribute__((__aligned__(8))) shared; /* 136 32 */
struct anon_vma_name * anon_name; /* 168 8 */
struct vm_userfaultfd_ctx vm_userfaultfd_ctx; /* 176 8 */
/* size: 192, cachelines: 3, members: 18 */
/* sum members: 176, holes: 2, sum holes: 8 */
/* padding: 8 */
/* forced alignments: 2, forced holes: 1, sum forced holes: 4 */
} __attribute__((__aligned__(64)));
Memory consumption per 1000 VMAs becomes 48 pages:
slabinfo after vm_area_struct changes:
<name> ... <objsize> <objperslab> <pagesperslab> : ...
vm_area_struct ... 192 42 2 : ...
Link: https://lkml.kernel.org/r/20250213224655.1680278-14-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Tested-by: Shivank Garg <shivankg@amd.com>
Link: https://lkml.kernel.org/r/5e19ec93-8307-47c2-bb13-3ddf7150624e@amd.com
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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rw_semaphore is a sizable structure of 40 bytes and consumes considerable
space for each vm_area_struct. However vma_lock has two important
specifics which can be used to replace rw_semaphore with a simpler
structure:
1. Readers never wait. They try to take the vma_lock and fall back to
mmap_lock if that fails.
2. Only one writer at a time will ever try to write-lock a vma_lock
because writers first take mmap_lock in write mode. Because of these
requirements, full rw_semaphore functionality is not needed and we can
replace rw_semaphore and the vma->detached flag with a refcount
(vm_refcnt).
When vma is in detached state, vm_refcnt is 0 and only a call to
vma_mark_attached() can take it out of this state. Note that unlike
before, now we enforce both vma_mark_attached() and vma_mark_detached() to
be done only after vma has been write-locked. vma_mark_attached() changes
vm_refcnt to 1 to indicate that it has been attached to the vma tree.
When a reader takes read lock, it increments vm_refcnt, unless the top
usable bit of vm_refcnt (0x40000000) is set, indicating presence of a
writer. When writer takes write lock, it sets the top usable bit to
indicate its presence. If there are readers, writer will wait using newly
introduced mm->vma_writer_wait. Since all writers take mmap_lock in write
mode first, there can be only one writer at a time. The last reader to
release the lock will signal the writer to wake up. refcount might
overflow if there are many competing readers, in which case read-locking
will fail. Readers are expected to handle such failures.
In summary:
1. all readers increment the vm_refcnt;
2. writer sets top usable (writer) bit of vm_refcnt;
3. readers cannot increment the vm_refcnt if the writer bit is set;
4. in the presence of readers, writer must wait for the vm_refcnt to drop
to 1 (plus the VMA_LOCK_OFFSET writer bit), indicating an attached vma
with no readers;
5. vm_refcnt overflow is handled by the readers.
While this vm_lock replacement does not yet result in a smaller
vm_area_struct (it stays at 256 bytes due to cacheline alignment), it
allows for further size optimization by structure member regrouping to
bring the size of vm_area_struct below 192 bytes.
[surenb@google.com: fix a crash due to vma_end_read() that should have been removed]
Link: https://lkml.kernel.org/r/20250220200208.323769-1-surenb@google.com
Link: https://lkml.kernel.org/r/20250213224655.1680278-13-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Tested-by: Shivank Garg <shivankg@amd.com>
Link: https://lkml.kernel.org/r/5e19ec93-8307-47c2-bb13-3ddf7150624e@amd.com
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
vma_iter_store() functions can be used both when adding a new vma and when
updating an existing one. However for existing ones we do not need to
mark them attached as they are already marked that way. With
vma->detached being a separate flag, double-marking a vmas as attached or
detached is not an issue because the flag will simply be overwritten with
the same value. However once we fold this flag into the refcount later in
this series, re-attaching or re-detaching a vma becomes an issue since
these operations will be incrementing/decrementing a refcount.
Introduce vma_iter_store_new() and vma_iter_store_overwrite() to replace
vma_iter_store() and avoid re-attaching a vma during vma update. Add
assertions in vma_mark_attached()/vma_mark_detached() to catch invalid
usage. Update vma tests to check for vma detached state correctness.
Link: https://lkml.kernel.org/r/20250213224655.1680278-5-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Tested-by: Shivank Garg <shivankg@amd.com>
Link: https://lkml.kernel.org/r/5e19ec93-8307-47c2-bb13-3ddf7150624e@amd.com
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Current implementation does not set detached flag when a VMA is first
allocated. This does not represent the real state of the VMA, which is
detached until it is added into mm's VMA tree. Fix this by marking new
VMAs as detached and resetting detached flag only after VMA is added into
a tree.
Introduce vma_mark_attached() to make the API more readable and to
simplify possible future cleanup when vma->vm_mm might be used to indicate
detached vma and vma_mark_attached() will need an additional mm parameter.
Link: https://lkml.kernel.org/r/20250213224655.1680278-4-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Tested-by: Shivank Garg <shivankg@amd.com>
Link: https://lkml.kernel.org/r/5e19ec93-8307-47c2-bb13-3ddf7150624e@amd.com
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Back when per-vma locks were introduces, vm_lock was moved out of
vm_area_struct in [1] because of the performance regression caused by
false cacheline sharing. Recent investigation [2] revealed that the
regressions is limited to a rather old Broadwell microarchitecture and
even there it can be mitigated by disabling adjacent cacheline
prefetching, see [3].
Splitting single logical structure into multiple ones leads to more
complicated management, extra pointer dereferences and overall less
maintainable code. When that split-away part is a lock, it complicates
things even further. With no performance benefits, there are no reasons
for this split. Merging the vm_lock back into vm_area_struct also allows
vm_area_struct to use SLAB_TYPESAFE_BY_RCU later in this patchset. Move
vm_lock back into vm_area_struct, aligning it at the cacheline boundary
and changing the cache to be cacheline-aligned as well. With kernel
compiled using defconfig, this causes VMA memory consumption to grow from
160 (vm_area_struct) + 40 (vm_lock) bytes to 256 bytes:
slabinfo before:
<name> ... <objsize> <objperslab> <pagesperslab> : ...
vma_lock ... 40 102 1 : ...
vm_area_struct ... 160 51 2 : ...
slabinfo after moving vm_lock:
<name> ... <objsize> <objperslab> <pagesperslab> : ...
vm_area_struct ... 256 32 2 : ...
Aggregate VMA memory consumption per 1000 VMAs grows from 50 to 64 pages,
which is 5.5MB per 100000 VMAs. Note that the size of this structure is
dependent on the kernel configuration and typically the original size is
higher than 160 bytes. Therefore these calculations are close to the
worst case scenario. A more realistic vm_area_struct usage before this
change is:
<name> ... <objsize> <objperslab> <pagesperslab> : ...
vma_lock ... 40 102 1 : ...
vm_area_struct ... 176 46 2 : ...
Aggregate VMA memory consumption per 1000 VMAs grows from 54 to 64 pages,
which is 3.9MB per 100000 VMAs. This memory consumption growth can be
addressed later by optimizing the vm_lock.
[1] https://lore.kernel.org/all/20230227173632.3292573-34-surenb@google.com/
[2] https://lore.kernel.org/all/ZsQyI%2F087V34JoIt@xsang-OptiPlex-9020/
[3] https://lore.kernel.org/all/CAJuCfpEisU8Lfe96AYJDZ+OM4NoPmnw9bP53cT_kbfP_pR+-2g@mail.gmail.com/
Link: https://lkml.kernel.org/r/20250213224655.1680278-3-surenb@google.com
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Shakeel Butt <shakeel.butt@linux.dev>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com>
Tested-by: Shivank Garg <shivankg@amd.com>
Link: https://lkml.kernel.org/r/5e19ec93-8307-47c2-bb13-3ddf7150624e@amd.com
Cc: Christian Brauner <brauner@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Klara Modin <klarasmodin@gmail.com>
Cc: Lokesh Gidra <lokeshgidra@google.com>
Cc: Mateusz Guzik <mjguzik@gmail.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@google.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Will Deacon <will@kernel.org>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Extend the guard region self tests to explicitly assert that guard regions
work correctly for functionality specific to file-backed and shmem
mappings.
In addition to testing all of the existing guard region functionality that
is currently tested against anonymous mappings against file-backed and
shmem mappings (except those which are exclusive to anonymous mapping), we
now also:
* Test that MADV_SEQUENTIAL does not cause unexpected readahead behaviour.
* Test that MAP_PRIVATE behaves as expected with guard regions installed in
both a shared and private mapping of an fd.
* Test that a read-only file can correctly establish guard regions.
* Test a probable fault-around case does not interfere with guard regions
(or vice-versa).
* Test that truncation does not eliminate guard regions.
* Test that hole punching functions as expected in the presence of guard
regions.
* Test that a read-only mapping of a memfd write sealed mapping can have
guard regions established within it and function correctly without
violation of the seal.
* Test that guard regions installed into a mapping of the anonymous zero
page function correctly.
Link: https://lkml.kernel.org/r/90c16bec5fcaafcd1700dfa3e9988c3e1aa9ac1d.1739469950.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Extend the guard region tests to allow for test fixture variants for anon,
shmem, and local file files.
This allows us to assert that each of the expected behaviours of anonymous
memory also applies correctly to file-backed (both shmem and an a file
created locally in the current working directory) and thus asserts the
same correctness guarantees as all the remaining tests do.
The fixture teardown is now performed in the parent process rather than
child forked ones, meaning cleanup is always performed, including
unlinking any generated temporary files.
Additionally the variant fixture data type now contains an enum value
indicating the type of backing store and the mmap() invocation is
abstracted to allow for the mapping of whichever backing store the variant
is testing.
We adjust tests as necessary to account for the fact they may now
reference files rather than anonymous memory.
Link: https://lkml.kernel.org/r/ab42228d2bd9b8aa18e9faebcd5c88732a7e5820.1739469950.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The feature formerly referred to as guard pages is more correctly referred
to as 'guard regions', as in fact no pages are ever allocated in the
process of installing the regions.
To avoid confusion, rename the tests accordingly.
[lorenzo.stoakes@oracle.com: fix guard regions invocation]
Link: https://lkml.kernel.org/r/13426c71-d069-4407-9340-b227ff8b8736@lucifer.local
Link: https://lkml.kernel.org/r/1c3cd04a3f69b5756b94bda701ac88325a9be18b.1739469950.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: "Paul E . McKenney" <paulmck@kernel.org>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Currently the mm selftests refuse to run if huge pages are not available
in the current system but this is an optional feature and not all the
tests actually require them. Change the test during startup to be
non-fatal and skip or omit tests which actually rely on having huge pages,
allowing the other tests to be run.
The gup_test does support using madvise() to configure huge pages but it
ignores the error code so we just let it run.
Link: https://lkml.kernel.org/r/20250212-kselftest-mm-no-hugepages-v1-2-44702f538522@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Nico Pache <npache@redhat.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Fix misspelling.
Link: https://lkml.kernel.org/r/77e0e915-36c3-4c95-84b8-0b73aaa17951@gmail.com
Signed-off-by: Eric Salem <ericsalem@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The thuge-gen test_mmap() and test_shmget() tests are repeatedly run for a
variety of sizes but always report the result of their test with the same
name, meaning that automated sysetms running the tests are unable to
distinguish between the various tests. Add the supplied sizes to the
logged test names to distinguish between runs.
My test automation was getting pretty confused about what was going on
- the test names are a pretty important external interface.
Link: https://lkml.kernel.org/r/20250204-kselftest-mm-fix-dups-v1-1-6afe417ef4bb@kernel.org
Fixes: b38bd9b2c448 ("selftests/mm: thuge-gen: conform to TAP format output")
Signed-off-by: Mark Brown <broonie@kernel.org>
Reviewed-by: Dev Jain <dev.jain@arm.com>
Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The adj_start calculation has been a constant source of confusion in the
VMA merge code.
There are two cases to consider, one where we adjust the start of the
vmg->middle VMA (i.e. the vmg->__adjust_middle_start merge flag is set),
in which case adj_start is calculated as:
(1) adj_start = vmg->end - vmg->middle->vm_start
And the case where we adjust the start of the vmg->next VMA (i.e. the
vmg->__adjust_next_start merge flag is set), in which case adj_start is
calculated as:
(2) adj_start = -(vmg->middle->vm_end - vmg->end)
We apply (1) thusly:
vmg->middle->vm_start =
vmg->middle->vm_start + vmg->end - vmg->middle->vm_start
Which simplifies to:
vmg->middle->vm_start = vmg->end
Similarly, we apply (2) as:
vmg->next->vm_start =
vmg->next->vm_start + -(vmg->middle->vm_end - vmg->end)
Noting that for these VMAs to be mergeable vmg->middle->vm_end ==
vmg->next->vm_start and so this simplifies to:
vmg->next->vm_start =
vmg->next->vm_start + -(vmg->next->vm_start - vmg->end)
Which simplifies to:
vmg->next->vm_start = vmg->end
Therefore in each case, we simply need to adjust the start of the VMA to
vmg->end (!) and can do away with this adj_start calculation. The only
caveat is that we must ensure we update the vm_pgoff field correctly.
We therefore abstract this entire calculation to a new function
vmg_adjust_set_range() which performs this calculation and sets the
adjusted VMA's new range using the general vma_set_range() function.
We also must update vma_adjust_trans_huge() which expects the
now-abstracted adj_start parameter. It turns out this is wholly
unnecessary.
In vma_adjust_trans_huge() the relevant code is:
if (adjust_next > 0) {
struct vm_area_struct *next = find_vma(vma->vm_mm, vma->vm_end);
unsigned long nstart = next->vm_start;
nstart += adjust_next;
split_huge_pmd_if_needed(next, nstart);
}
The only case where this is relevant is when vmg->__adjust_middle_start is
specified (in which case adj_next would have been positive), i.e. the one
in which the vma specified is vmg->prev and this the sought 'next' VMA
would be vmg->middle.
We can therefore eliminate the find_vma() invocation altogether and simply
provide the vmg->middle VMA in this instance, or NULL otherwise.
Again we have an adj_next offset calculation:
next->vm_start + vmg->end - vmg->middle->vm_start
Where next == vmg->middle this simplifies to vmg->end as previously
demonstrated.
Therefore nstart is equal to vmg->end, which is already passed to
vma_adjust_trans_huge() via the 'end' parameter and so this code (rather
delightfully) simplifies to:
if (next)
split_huge_pmd_if_needed(next, end);
With these changes in place, it becomes silly for commit_merge() to return
vmg->target, as it is always the same and threaded through vmg, so we
finally change commit_merge() to return an error value once again.
This patch has no change in functional behaviour.
Link: https://lkml.kernel.org/r/7bce2cd4b5afb56211822835d145471280c3dccc.1738326519.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Introduce internal vmg->__adjust_middle_start and vmg->__adjust_next_start
merge flags, enabling us to indicate to commit_merge() that we are
performing a merge which either spans only part of vmg->middle, or part of
vmg->next respectively.
In the former instance, we change the start of vmg->middle to match the
attributes of vmg->prev, without spanning all of vmg->middle.
This implies that vmg->prev->vm_end and vmg->middle->vm_start are both
increased to form the new merged VMA (vmg->prev) and the new subsequent
VMA (vmg->middle).
In the latter case, we change the end of vmg->middle to match the
attributes of vmg->next, without spanning all of vmg->next.
This implies that vmg->middle->vm_end and vmg->next->vm_start are both
decreased to form the new merged VMA (vmg->next) and the new prior VMA
(vmg->middle).
Since we now have a stable set of prev, middle, next VMAs threaded through
vmg and with these flags set know what is happening, we can perform the
calculation in commit_merge() instead.
This allows us to drop the confusing adj_start parameter and instead pass
semantic information to commit_merge().
In the latter case the -(middle->vm_end - start) calculation becomes
-(middle->vm-end - vmg->end), however this is correct as vmg->end is set
to the start parameter.
This is because in this case (rather confusingly), we manipulate
vmg->middle, but ultimately return vmg->next, whose range will be
correctly specified. At this point vmg->start, end is the new range for
the prior VMA rather than the merged one.
This patch has no change in functional behaviour.
Link: https://lkml.kernel.org/r/bcec0cd980b373a5eb02236cb033034ce1effe42.1738326519.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The current VMA merge mechanism contains a number of confusing mechanisms
around removal of VMAs on merge and the shrinking of the VMA adjacent to
vma->target in the case of merges which result in a partial merge with
that adjacent VMA.
Since we now have a STABLE set of VMAs - prev, middle, next - we are now
able to have the caller of commit_merge() explicitly tell us which VMAs
need deleting, using newly introduced internal VMA merge flags.
Doing so allows us to embed this state within the VMG and remove the
confusing remove, remove2 parameters from commit_merge().
We additionally are able to eliminate the highly confusing and misleading
'expanded' parameter - a parameter that in reality refers to whether or
not the return VMA is the target one or the one immediately adjacent.
We can infer which is the case from whether or not the adj_start parameter
is negative. This also allows us to simplify further logic around
iterator configuration and VMA iterator stores.
Doing so means we can also eliminate the adjust parameter, as we are able
to infer which VMA ought to be adjusted from adj_start - a positive value
implies we adjust the start of 'middle', a negative one implies we adjust
the start of 'next'.
We are then able to have commit_merge() explicitly return the target VMA,
or NULL on inability to pre-allocate memory. Errors were previously
filtered so behaviour does not change.
We additionally move from the slightly odd use of a bitwise-flag enum
vmg->merge_flags field to vmg bitfields.
This patch has no change in functional behaviour.
Link: https://lkml.kernel.org/r/7bf2ed24af68aac18672b7acebbd9102f48c5b03.1738326519.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm: further simplify VMA merge operation", v3.
While significant efforts have been made to improve the VMA merge
operation, there remains remnants of the bad (or rather confusing) old
days, which make the code difficult to understand, more bug prone and thus
harder to modify.
This series attempts to significantly improve matters in a number of
respects - with a focus on simplifying the commit_merge() function which
actually actions the merge operation - and importantly, adjusting the two
most confusing merge cases - those in which we 'adjust' the VMA
immediately adjacent to the one being merged.
One source of confusion are the VMAs being threaded through the operation
themselves - vmg->prev, vmg->vma and vmg->next.
At the start of the operation, vmg->vma is either NULL if a new VMA is
propose to be added, or if not then a pointer to an existing VMA being
modified, and prev/next are (perhaps not present) VMAs sat immediately
before and after the range specified in vmg->start, end, respectively.
However, during the VMA merge operation, we change vmg->start, end and
pgoff to span the newly merged range and vmg->vma to either be:
a. The ultimately returned VMA (in most cases) or b. A VMA which we will
manipulate, but ultimately instead return vmg->next.
Case b. especially here is confusing for somebody reading this code, but
the fact we update this state, along with vmg->start, end, pgoff only
makes matters worse.
We simplify things by replacing vmg->vma with vmg->middle and never
changing it - this is always either NULL (for a new VMA) or the VMA being
modified between vmg->prev and vmg->next.
We further simplify by placing the merged VMA in a new vmg->target field -
whether case b. above is the case or not. The reader of the code can now
simply rely on vmg->middle being the middle VMA and vmg->target being the
ultimately merged VMA.
We additionally tackle the confusing cases where we 'adjust' VMAs other
than the one we ultimately return as the merged VMA (this includes case b.
above). These are:
(1)
merge
<----------->
|------||--------| |------------|---|
| prev || middle | -> | target | m |
|------||--------| |------------|---|
In which case middle must be adjusted so middle->vm_start is increased as
well as performing the merge.
(2) (equivalent to case b. above)
<------------->
|---------||------| |---|-------------|
| middle || next | -> | m | target |
|---------||------| |---|-------------|
In which case next must be adjusted so next->vm_start is decreased as well
as performing the merge.
This cases have previously been performed by calculating and passing
around a dubious and confusing 'adj_start' parameter along side a pointer
to an 'adjust' VMA indicating which VMA requires additional adjustment
(middle in case 1 and next in case 2).
With the VMG structure in place we are able to avoid this by simply
setting a merge flag to describe each case:
(1) Sets the vmg->__adjust_middle_start flag
(2) Sets the vmg->__adjust_next_start flag
By doing so it turns out we can vastly simplify the logic and calculate
what is required to perform the operation.
Taken together the refactorings make it far easier to understand what is
being done even in these more confusing cases, make the code far more
maintainable, debuggable, and testable, providing more internal state
indicating what is happening in the merge operation.
The changes have no functional net impact on the merge operation and
everything should still behave as it did before.
This patch (of 5):
The merge code, while much improved, still has a number of points of
confusion. As part of a broader series cleaning this up to make this more
maintainable, we start by addressing some confusion around
vma_merge_struct fields.
So far, the caller either provides no vmg->vma (a new VMA) or supplies the
existing VMA which is being altered, setting vmg->start,end,pgoff to the
proposed VMA dimensions.
vmg->vma is then updated, as are vmg->start,end,pgoff as the merge process
proceeds and the appropriate merge strategy is determined.
This is rather confusing, as vmg->vma starts off as the 'middle' VMA
between vmg->prev,next, but becomes the 'target' VMA, except in one
specific edge case (merge next, shrink middle).
Int his patch we introduce vmg->middle to describe the VMA that is between
vmg->prev and vmg->next, and does NOT change during the merge operation.
We replace vmg->vma with vmg->target, and use this only during the merge
operation itself.
Aside from the merge right, shrink middle case, this becomes the VMA that
forms the basis of the VMA that is returned. This edge case can be
addressed in a future commit.
We also add a number of comments to explain what is going on.
Finally, we adjust the ASCII diagrams showing each merge case in
vma_merge_existing_range() to be clearer - the arrow range previously
showed the vmg->start, end spanned area, but it is clearer to change this
to show the final merged VMA.
This patch has no change in functional behaviour.
Link: https://lkml.kernel.org/r/cover.1738326519.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/4dfe60f1419d55e5d0516f56349695d73a57184c.1738326519.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Now split_huge_page*() supports shmem THP split to any lower order. Test
it.
The test now reads file content out after split to check if the split
corrupts the file data.
Link: https://lkml.kernel.org/r/20250122161928.1240637-3-ziy@nvidia.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Tested-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Commit acd7ccb284b8 ("mm: shmem: add large folio support for tmpfs")
changes huge=always to allocate THP/mTHP based on write size and
split_huge_page_test does not write PMD size data, so file-back THP is not
created during the test. Fix it by writing PMD size data.
Link: https://lkml.kernel.org/r/20250122161928.1240637-1-ziy@nvidia.com
Signed-off-by: Zi Yan <ziy@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Kirill A. Shuemov <kirill.shutemov@linux.intel.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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We noticed that uffd-stress test was always failing to run when invoked
for the hugetlb profiles on x86_64 systems with a processor count of 64 or
bigger:
...
# ------------------------------------
# running ./uffd-stress hugetlb 128 32
# ------------------------------------
# ERROR: invalid MiB (errno=9, @uffd-stress.c:459)
...
# [FAIL]
not ok 3 uffd-stress hugetlb 128 32 # exit=1
...
The problem boils down to how run_vmtests.sh (mis)calculates the size of
the region it feeds to uffd-stress. The latter expects to see an amount
of MiB while the former is just giving out the number of free hugepages
halved down. This measurement discrepancy ends up violating uffd-stress'
assertion on number of hugetlb pages allocated per CPU, causing it to bail
out with the error above.
This commit fixes that issue by adjusting run_vmtests.sh's
half_ufd_size_MB calculation so it properly renders the region size in
MiB, as expected, while maintaining all of its original constraints in
place.
Link: https://lkml.kernel.org/r/20250218192251.53243-1-aquini@redhat.com
Fixes: 2e47a445d7b3 ("selftests/mm: run_vmtests.sh: fix hugetlb mem size calculation")
Signed-off-by: Rafael Aquini <raquini@redhat.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Add test to check for the infinite loop caused by the inability
to parse a late test plan.
The test parses the following output:
TAP version 13
ok 4 test4
1..4
Link: https://lore.kernel.org/r/20250313192714.1380005-1-rmoar@google.com
Signed-off-by: Rae Moar <rmoar@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <shuah@kernel.org>
|
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A bug was identified where the KTAP below caused an infinite loop:
TAP version 13
ok 4 test_case
1..4
The infinite loop was caused by the parser not parsing a test plan
if following a test result line.
Fix this bug by parsing test plan line to avoid the infinite loop.
Link: https://lore.kernel.org/r/20250313192714.1380005-1-rmoar@google.com
Signed-off-by: Rae Moar <rmoar@google.com>
Reviewed-by: David Gow <davidgow@google.com>
Signed-off-by: Shuah Khan <shuah@kernel.org>
|
|
The SO_RCVLOWAT option is defined as 18 in the selftest header,
which matches the generic definition. However, on powerpc,
SO_RCVLOWAT is defined as 16. This discrepancy causes
sol_socket_sockopt() to fail with the default switch case on powerpc.
This commit fixes by defining SO_RCVLOWAT as 16 for powerpc.
Signed-off-by: Saket Kumar Bhaskar <skb99@linux.ibm.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Link: https://lore.kernel.org/bpf/20250311084647.3686544-1-skb99@linux.ibm.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
The strncmp benchmark uses the bpf_strncmp helper and a hand-written
loop to compare two strings. The values of the strings are filled from
userspace. One of the strings is non-const (in .bss) while the other is
const (in .rodata) since that is the requirement of bpf_strncmp.
The problem is that in the hand-written loop, Clang optimizes the reads
from the const string to always return 0 which breaks the benchmark.
Use barrier_var to prevent the optimization.
The effect can be seen on the strncmp-no-helper variant.
Before this change:
# ./bench strncmp-no-helper
Setting up benchmark 'strncmp-no-helper'...
Benchmark 'strncmp-no-helper' started.
Iter 0 (112.309us): hits 0.000M/s ( 0.000M/prod), drops 0.000M/s, total operations 0.000M/s
Iter 1 (-23.238us): hits 0.000M/s ( 0.000M/prod), drops 0.000M/s, total operations 0.000M/s
Iter 2 ( 58.994us): hits 0.000M/s ( 0.000M/prod), drops 0.000M/s, total operations 0.000M/s
Iter 3 (-30.466us): hits 0.000M/s ( 0.000M/prod), drops 0.000M/s, total operations 0.000M/s
Iter 4 ( 29.996us): hits 0.000M/s ( 0.000M/prod), drops 0.000M/s, total operations 0.000M/s
Iter 5 ( 16.949us): hits 0.000M/s ( 0.000M/prod), drops 0.000M/s, total operations 0.000M/s
Iter 6 (-60.035us): hits 0.000M/s ( 0.000M/prod), drops 0.000M/s, total operations 0.000M/s
Summary: hits 0.000 ± 0.000M/s ( 0.000M/prod), drops 0.000 ± 0.000M/s, total operations 0.000 ± 0.000M/s
After this change:
# ./bench strncmp-no-helper
Setting up benchmark 'strncmp-no-helper'...
Benchmark 'strncmp-no-helper' started.
Iter 0 ( 77.711us): hits 5.534M/s ( 5.534M/prod), drops 0.000M/s, total operations 5.534M/s
Iter 1 ( 11.215us): hits 6.006M/s ( 6.006M/prod), drops 0.000M/s, total operations 6.006M/s
Iter 2 (-14.253us): hits 5.931M/s ( 5.931M/prod), drops 0.000M/s, total operations 5.931M/s
Iter 3 ( 59.087us): hits 6.005M/s ( 6.005M/prod), drops 0.000M/s, total operations 6.005M/s
Iter 4 (-21.379us): hits 6.010M/s ( 6.010M/prod), drops 0.000M/s, total operations 6.010M/s
Iter 5 (-20.310us): hits 5.861M/s ( 5.861M/prod), drops 0.000M/s, total operations 5.861M/s
Iter 6 ( 53.937us): hits 6.004M/s ( 6.004M/prod), drops 0.000M/s, total operations 6.004M/s
Summary: hits 5.969 ± 0.061M/s ( 5.969M/prod), drops 0.000 ± 0.000M/s, total operations 5.969 ± 0.061M/s
Fixes: 9c42652f8be3 ("selftests/bpf: Add benchmark for bpf_strncmp() helper")
Suggested-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Viktor Malik <vmalik@redhat.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/bpf/20250313122852.1365202-1-vmalik@redhat.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
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Venkat reported a compilation error for BPF selftests on PowerPC [0].
The crux of the error is the following message:
In file included from progs/arena_spin_lock.c:7:
/root/bpf-next/tools/testing/selftests/bpf/bpf_arena_spin_lock.h:122:8:
error: member reference base type '__attribute__((address_space(1)))
u32' (aka '__attribute__((address_space(1))) unsigned int') is not a
structure or union
122 | old = atomic_read(&lock->val);
This is because PowerPC overrides the qspinlock type changing the
lock->val member's type from atomic_t to u32.
To remedy this, import the asm-generic version in the arena spin lock
header, name it __qspinlock (since it's aliased to arena_spinlock_t, the
actual name hardly matters), and adjust the selftest to not depend on
the type in vmlinux.h.
[0]: https://lore.kernel.org/bpf/7bc80a3b-d708-4735-aa3b-6a8c21720f9d@linux.ibm.com
Fixes: 88d706ba7cc5 ("selftests/bpf: Introduce arena spin lock")
Reported-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Venkat Rao Bagalkote <venkat88@linux.ibm.com>
Link: https://lore.kernel.org/bpf/20250311154244.3775505-1-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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We are missing setting error code in do_loader() when
bpf_object__open_file() fails. This means the command's exit status code
will be successful, even though the operation failed. So make sure to
return the correct error code. To maintain consistency with other
locations where bpf_object__open_file() is called, return -1.
[0] Closes: https://github.com/libbpf/bpftool/issues/156
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Sewon Nam <swnam0729@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: Quentin Monnet <qmo@kernel.org>
Reviewed-by: Quentin Monnet <qmo@kernel.org>
Link: https://lore.kernel.org/bpf/d3b5b4b4-19bb-4619-b4dd-86c958c4a367@stanley.mountain/t/#u
Link: https://lore.kernel.org/bpf/20250311031238.14865-1-swnam0729@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
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This test exercises the kernel flag added to security_bpf by
effectively blocking light-skeletons from loading while allowing
normal skeletons to function as-is. Since this should work with any
arbitrary BPF program, an existing program from LSKELS_EXTRA was
used as a test payload.
Signed-off-by: Blaise Boscaccy <bboscaccy@linux.microsoft.com>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/r/20250310221737.821889-3-bboscaccy@linux.microsoft.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Certain bpf syscall subcommands are available for usage from both
userspace and the kernel. LSM modules or eBPF gatekeeper programs may
need to take a different course of action depending on whether or not
a BPF syscall originated from the kernel or userspace.
Additionally, some of the bpf_attr struct fields contain pointers to
arbitrary memory. Currently the functionality to determine whether or
not a pointer refers to kernel memory or userspace memory is exposed
to the bpf verifier, but that information is missing from various LSM
hooks.
Here we augment the LSM hooks to provide this data, by simply passing
a boolean flag indicating whether or not the call originated in the
kernel, in any hook that contains a bpf_attr struct that corresponds
to a subcommand that may be called from the kernel.
Signed-off-by: Blaise Boscaccy <bboscaccy@linux.microsoft.com>
Acked-by: Song Liu <song@kernel.org>
Acked-by: Paul Moore <paul@paul-moore.com>
Link: https://lore.kernel.org/r/20250310221737.821889-2-bboscaccy@linux.microsoft.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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Replace comma between expressions with semicolons.
Using a ',' in place of a ';' can have unintended side effects.
Although that is not the case here, it is seems best to use ';'
unless ',' is intended.
Found by inspection.
No functional change intended.
Compile tested only.
Signed-off-by: Chen Ni <nichen@iscas.ac.cn>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Anton Protopopov <aspsk@isovalent.com>
Link: https://lore.kernel.org/bpf/20250310032045.651068-1-nichen@iscas.ac.cn
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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The Makefile uses the exit code of the `llvm-config --link-static --libs`
command to choose between statically-linked and dynamically-linked LLVMs.
The stdout and stderr of that command are redirected to /dev/null.
To redirect the output the "&>" construction is used, which might not be
supported by /bin/sh, which is executed by make for $(shell ...) commands.
On such systems the test will fail even if static LLVM is actually
supported. Replace "&>" by ">/dev/null 2>&1" to fix this.
Fixes: 2a9d30fac818 ("selftests/bpf: Support dynamically linking LLVM if static is not available")
Signed-off-by: Anton Protopopov <aspsk@isovalent.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/bpf/20250310145112.1261241-1-aspsk@isovalent.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
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The BPF cpumask selftests are currently run twice in
test_progs/cpumask.c, once by traversing cpumask_success_testcases, and
once by invoking RUN_TESTS(cpumask_success). Remove the invocation of
RUN_TESTS to properly run the selftests only once.
Now that the tests are run only through cpumask_success_testscases, add
to it the missing test_refcount_null_tracking testcase. Also remove the
__success annotation from it, since it is now loaded and invoked by the
runner.
Signed-off-by: Emil Tsalapatis (Meta) <emil@etsalapatis.com>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250309230427.26603-5-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
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Add selftests for the bpf_cpumask_populate helper that sets a
bpf_cpumask to a bit pattern provided by a BPF program.
Signed-off-by: Emil Tsalapatis (Meta) <emil@etsalapatis.com>
Acked-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250309230427.26603-3-emil@etsalapatis.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
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test_lwt_seg6local.sh isn't used by the BPF CI.
Add a new file in the test_progs framework to migrate the tests done by
test_lwt_seg6local.sh. It uses the same network topology and the same BPF
programs located in progs/test_lwt_seg6local.c.
Use the network helpers instead of `nc` to exchange the final packet.
Remove test_lwt_seg6local.sh and its Makefile entry.
Signed-off-by: Bastien Curutchet (eBPF Foundation) <bastien.curutchet@bootlin.com>
Link: https://lore.kernel.org/r/20250307-seg6local-v1-2-990fff8f180d@bootlin.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
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Some routes in fb00:: are initialized during setup, even though they
aren't needed by the test as the UDP packets will travel through the
lightweight tunnels.
Remove these unnecessary routes.
Signed-off-by: Bastien Curutchet (eBPF Foundation) <bastien.curutchet@bootlin.com>
Link: https://lore.kernel.org/r/20250307-seg6local-v1-1-990fff8f180d@bootlin.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
