| Age | Commit message (Collapse) | Author |
|---|
|
The freeing of special fields in map value may acquire a spin-lock
(e.g., the freeing of bpf_timer), however, the lookup_and_delete_elem
procedure has already held a raw-spin-lock, which violates the lockdep
rule.
The running context of __htab_map_lookup_and_delete_elem() has already
disabled the migration. Therefore, it is OK to invoke free_htab_elem()
after unlocking the bucket lock.
Fix the potential problem by freeing element after unlocking bucket lock
in __htab_map_lookup_and_delete_elem().
Signed-off-by: Hou Tao <houtao1@huawei.com>
Link: https://lore.kernel.org/r/20250117101816.2101857-4-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Use goto statement to bail out early when the target element is not
found, instead of using a large else branch to handle the more likely
case. This change doesn't affect functionality and simply make the code
cleaner.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@kernel.org>
Link: https://lore.kernel.org/r/20250117101816.2101857-3-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
When bpf_timer is used in LRU hash map, calling check_and_free_fields()
in htab_lru_map_delete_node() will invoke bpf_timer_cancel_and_free() to
free the bpf_timer. If the timer is running on other CPUs,
hrtimer_cancel() will invoke hrtimer_cancel_wait_running() to spin on
current CPU to wait for the completion of the hrtimer callback.
Considering that the deletion has already acquired a raw-spin-lock
(bucket lock). To reduce the time holding the bucket lock, move the
invocation of check_and_free_fields() out of bucket lock. However,
because htab_lru_map_delete_node() is invoked with LRU raw spin lock
being held, the freeing of special fields still happens in a locked
scope.
Signed-off-by: Hou Tao <houtao1@huawei.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@kernel.org>
Link: https://lore.kernel.org/r/20250117101816.2101857-2-houtao@huaweicloud.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timer fixes from Borislav Petkov:
- Reset hrtimers correctly when a CPU hotplug state traversal happens
"half-ways" and leaves hrtimers not (re-)initialized properly
- Annotate accesses to a timer group's ignore flag to prevent KCSAN
from raising data_race warnings
- Make sure timer group initialization is visible to timer tree walkers
and avoid a hypothetical race
- Fix another race between CPU hotplug and idle entry/exit where timers
on a fully idle system are getting ignored
- Fix a case where an ignored signal is still being handled which it
shouldn't be
* tag 'timers_urgent_for_v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
hrtimers: Handle CPU state correctly on hotplug
timers/migration: Annotate accesses to ignore flag
timers/migration: Enforce group initialization visibility to tree walkers
timers/migration: Fix another race between hotplug and idle entry/exit
signal/posixtimers: Handle ignore/blocked sequences correctly
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Borislav Petkov:
- Do not adjust the weight of empty group entities and avoid
scheduling artifacts
- Avoid scheduling lag by computing lag properly and thus address
an EEVDF entity placement issue
* tag 'sched_urgent_for_v6.13' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched/fair: Fix update_cfs_group() vs DELAY_DEQUEUE
sched/fair: Fix EEVDF entity placement bug causing scheduling lag
|
|
Although the previous patch can avoid ps and ps UAF for _do_serial, it
can not avoid potential UAF issue for reorder_work. This issue can
happen just as below:
crypto_request crypto_request crypto_del_alg
padata_do_serial
...
padata_reorder
// processes all remaining
// requests then breaks
while (1) {
if (!padata)
break;
...
}
padata_do_serial
// new request added
list_add
// sees the new request
queue_work(reorder_work)
padata_reorder
queue_work_on(squeue->work)
...
<kworker context>
padata_serial_worker
// completes new request,
// no more outstanding
// requests
crypto_del_alg
// free pd
<kworker context>
invoke_padata_reorder
// UAF of pd
To avoid UAF for 'reorder_work', get 'pd' ref before put 'reorder_work'
into the 'serial_wq' and put 'pd' ref until the 'serial_wq' finish.
Fixes: bbefa1dd6a6d ("crypto: pcrypt - Avoid deadlock by using per-instance padata queues")
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
|
|
A bug was found when run ltp test:
BUG: KASAN: slab-use-after-free in padata_find_next+0x29/0x1a0
Read of size 4 at addr ffff88bbfe003524 by task kworker/u113:2/3039206
CPU: 0 PID: 3039206 Comm: kworker/u113:2 Kdump: loaded Not tainted 6.6.0+
Workqueue: pdecrypt_parallel padata_parallel_worker
Call Trace:
<TASK>
dump_stack_lvl+0x32/0x50
print_address_description.constprop.0+0x6b/0x3d0
print_report+0xdd/0x2c0
kasan_report+0xa5/0xd0
padata_find_next+0x29/0x1a0
padata_reorder+0x131/0x220
padata_parallel_worker+0x3d/0xc0
process_one_work+0x2ec/0x5a0
If 'mdelay(10)' is added before calling 'padata_find_next' in the
'padata_reorder' function, this issue could be reproduced easily with
ltp test (pcrypt_aead01).
This can be explained as bellow:
pcrypt_aead_encrypt
...
padata_do_parallel
refcount_inc(&pd->refcnt); // add refcnt
...
padata_do_serial
padata_reorder // pd
while (1) {
padata_find_next(pd, true); // using pd
queue_work_on
...
padata_serial_worker crypto_del_alg
padata_put_pd_cnt // sub refcnt
padata_free_shell
padata_put_pd(ps->pd);
// pd is freed
// loop again, but pd is freed
// call padata_find_next, UAF
}
In the padata_reorder function, when it loops in 'while', if the alg is
deleted, the refcnt may be decreased to 0 before entering
'padata_find_next', which leads to UAF.
As mentioned in [1], do_serial is supposed to be called with BHs disabled
and always happen under RCU protection, to address this issue, add
synchronize_rcu() in 'padata_free_shell' wait for all _do_serial calls
to finish.
[1] https://lore.kernel.org/all/20221028160401.cccypv4euxikusiq@parnassus.localdomain/
[2] https://lore.kernel.org/linux-kernel/jfjz5d7zwbytztackem7ibzalm5lnxldi2eofeiczqmqs2m7o6@fq426cwnjtkm/
Fixes: b128a3040935 ("padata: allocate workqueue internally")
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Signed-off-by: Qu Zicheng <quzicheng@huawei.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
|
|
Add helpers for pd to get/put refcnt to make code consice.
Signed-off-by: Chen Ridong <chenridong@huawei.com>
Acked-by: Daniel Jordan <daniel.m.jordan@oracle.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
|
|
Module functions can be set to set_ftrace_filter before the module is
loaded.
# echo :mod:snd_hda_intel > set_ftrace_filter
This will enable all the functions for the module snd_hda_intel. If that
module is not loaded, it is "cached" in the trace array for when the
module is loaded, its functions will be traced.
But this is not implemented in the kernel command line. That's because the
kernel command line filtering is added very early in boot up as it is
needed to be done before boot time function tracing can start, which is
also available very early in boot up. The code used by the
"set_ftrace_filter" file can not be used that early as it depends on some
other initialization to occur first. But some of the functions can.
Implement the ":mod:" feature of "set_ftrace_filter" in the kernel command
line parsing. Now function tracing on just a single module that is loaded
at boot up can be done.
Adding:
ftrace=function ftrace_filter=:mod:sna_hda_intel
To the kernel command line will only enable the sna_hda_intel module
functions when the module is loaded, and it will start tracing.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Link: https://lore.kernel.org/20250116175832.34e39779@gandalf.local.home
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Adopt __free() and guard() for trace_fprobe.c to remove gotos.
Link: https://lore.kernel.org/173708043449.319651.12242878905778792182.stgit@mhiramat.roam.corp.google.com
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
This commit allows progs to elide a null check on statically known map
lookup keys. In other words, if the verifier can statically prove that
the lookup will be in-bounds, allow the prog to drop the null check.
This is useful for two reasons:
1. Large numbers of nullness checks (especially when they cannot fail)
unnecessarily pushes prog towards BPF_COMPLEXITY_LIMIT_JMP_SEQ.
2. It forms a tighter contract between programmer and verifier.
For (1), bpftrace is starting to make heavier use of percpu scratch
maps. As a result, for user scripts with large number of unrolled loops,
we are starting to hit jump complexity verification errors. These
percpu lookups cannot fail anyways, as we only use static key values.
Eliding nullness probably results in less work for verifier as well.
For (2), percpu scratch maps are often used as a larger stack, as the
currrent stack is limited to 512 bytes. In these situations, it is
desirable for the programmer to express: "this lookup should never fail,
and if it does, it means I messed up the code". By omitting the null
check, the programmer can "ask" the verifier to double check the logic.
Tests also have to be updated in sync with these changes, as the
verifier is more efficient with this change. Notable, iters.c tests had
to be changed to use a map type that still requires null checks, as it's
exercising verifier tracking logic w.r.t iterators.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/68f3ea96ff3809a87e502a11a4bd30177fc5823e.1736886479.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Previously, the verifier was treating all PTR_TO_STACK registers passed
to a helper call as potentially written to by the helper. However, all
calls to check_stack_range_initialized() already have precise access type
information available.
Rather than treat ACCESS_HELPER as a proxy for BPF_WRITE, pass
enum bpf_access_type to check_stack_range_initialized() to more
precisely track helper arguments.
One benefit from this precision is that registers tracked as valid
spills and passed as a read-only helper argument remain tracked after
the call. Rather than being marked STACK_MISC afterwards.
An additional benefit is the verifier logs are also more precise. For
this particular error, users will enjoy a slightly clearer message. See
included selftest updates for examples.
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/ff885c0e5859e0cd12077c3148ff0754cad4f7ed.1736886479.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
The print was missing a newline.
Signed-off-by: Daniel Xu <dxu@dxuuu.xyz>
Link: https://lore.kernel.org/r/59cbe18367b159cd470dc6d5c652524c1dc2b984.1736886479.git.dxu@dxuuu.xyz
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
|
|
Cross-merge networking fixes after downstream PR (net-6.13-rc8).
Conflicts:
drivers/net/ethernet/realtek/r8169_main.c
1f691a1fc4be ("r8169: remove redundant hwmon support")
152d00a91396 ("r8169: simplify setting hwmon attribute visibility")
https://lore.kernel.org/20250115122152.760b4e8d@canb.auug.org.au
Adjacent changes:
drivers/net/ethernet/broadcom/bnxt/bnxt.c
152f4da05aee ("bnxt_en: add support for rx-copybreak ethtool command")
f0aa6a37a3db ("eth: bnxt: always recalculate features after XDP clearing, fix null-deref")
drivers/net/ethernet/intel/ice/ice_type.h
50327223a8bb ("ice: add lock to protect low latency interface")
dc26548d729e ("ice: Fix quad registers read on E825")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
|
|
When the :mod: command is written into /sys/kernel/tracing/set_event (or
that file within an instance), if the module specified after the ":mod:"
is not yet loaded, it will store that string internally. When the module
is loaded, it will enable the events as if the module was loaded when the
string was written into the set_event file.
This can also be useful to enable events that are in the init section of
the module, as the events are enabled before the init section is executed.
This also works on the kernel command line:
trace_event=:mod:<module>
Will enable the events for <module> when it is loaded.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/20250116143533.514730995@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Add a :mod: command to enable only events from a given module from the
set_events file.
echo '*:mod:<module>' > set_events
Or
echo ':mod:<module>' > set_events
Will enable all events for that module. Specific events can also be
enabled via:
echo '<event>:mod:<module>' > set_events
Or
echo '<system>:<event>:mod:<module>' > set_events
Or
echo '*:<event>:mod:<module>' > set_events
The ":mod:" keyword is consistent with the function tracing filter to
enable functions from a given module.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: https://lore.kernel.org/20250116143533.214496360@goodmis.org
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Having a single group on a given level is enough to know this is the
top level, because a root has to have at least two children, unless that
root is the only group and the children are actual CPUs.
Simplify the test in tmigr_setup_groups() accordingly.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250114231507.21672-5-frederic@kernel.org
|
|
Consider a scenario where a CPU transitions from CPUHP_ONLINE to halfway
through a CPU hotunplug down to CPUHP_HRTIMERS_PREPARE, and then back to
CPUHP_ONLINE:
Since hrtimers_prepare_cpu() does not run, cpu_base.hres_active remains set
to 1 throughout. However, during a CPU unplug operation, the tick and the
clockevents are shut down at CPUHP_AP_TICK_DYING. On return to the online
state, for instance CFS incorrectly assumes that the hrtick is already
active, and the chance of the clockevent device to transition to oneshot
mode is also lost forever for the CPU, unless it goes back to a lower state
than CPUHP_HRTIMERS_PREPARE once.
This round-trip reveals another issue; cpu_base.online is not set to 1
after the transition, which appears as a WARN_ON_ONCE in enqueue_hrtimer().
Aside of that, the bulk of the per CPU state is not reset either, which
means there are dangling pointers in the worst case.
Address this by adding a corresponding startup() callback, which resets the
stale per CPU state and sets the online flag.
[ tglx: Make the new callback unconditionally available, remove the online
modification in the prepare() callback and clear the remaining
state in the starting callback instead of the prepare callback ]
Fixes: 5c0930ccaad5 ("hrtimers: Push pending hrtimers away from outgoing CPU earlier")
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20241220134421.3809834-1-koichiro.den@canonical.com
|
|
The group's ignore flag is:
_ read under the group's lock (idle entry, remote expiry)
_ turned on/off under the group's lock (idle entry, remote expiry)
_ turned on locklessly on idle exit
When idle entry or remote expiry clear the "ignore" flag of a group, the
operation must be synchronized against other concurrent idle entry or
remote expiry to make sure the related group timer is never missed. To
enforce this synchronization, both "ignore" clear and read are
performed under the group lock.
On the contrary, whether idle entry or remote expiry manage to observe
the "ignore" flag turned on by a CPU exiting idle is a matter of
optimization. If that flag set is missed or cleared concurrently, the
worst outcome is a migrator wasting time remotely handling a "ghost"
timer. This is why the ignore flag can be set locklessly.
Unfortunately, the related lockless accesses are bare and miss
appropriate annotations. KCSAN rightfully complains:
BUG: KCSAN: data-race in __tmigr_cpu_activate / print_report
write to 0xffff88842fc28004 of 1 bytes by task 0 on cpu 0:
__tmigr_cpu_activate
tmigr_cpu_activate
timer_clear_idle
tick_nohz_restart_sched_tick
tick_nohz_idle_exit
do_idle
cpu_startup_entry
kernel_init
do_initcalls
clear_bss
reserve_bios_regions
common_startup_64
read to 0xffff88842fc28004 of 1 bytes by task 0 on cpu 1:
print_report
kcsan_report_known_origin
kcsan_setup_watchpoint
tmigr_next_groupevt
tmigr_update_events
tmigr_inactive_up
__walk_groups+0x50/0x77
walk_groups
__tmigr_cpu_deactivate
tmigr_cpu_deactivate
__get_next_timer_interrupt
timer_base_try_to_set_idle
tick_nohz_stop_tick
tick_nohz_idle_stop_tick
cpuidle_idle_call
do_idle
Although the relevant accesses could be marked as data_race(), the
"ignore" flag being read several times within the same
tmigr_update_events() function is confusing and error prone. Prefer
reading it once in that function and make use of similar/paired accesses
elsewhere with appropriate comments when necessary.
Reported-by: kernel test robot <oliver.sang@intel.com>
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250114231507.21672-4-frederic@kernel.org
Closes: https://lore.kernel.org/oe-lkp/202501031612.62e0c498-lkp@intel.com
|
|
Commit 2522c84db513 ("timers/migration: Fix another race between hotplug
and idle entry/exit") fixed yet another race between idle exit and CPU
hotplug up leading to a wrong "0" value migrator assigned to the top
level. However there is yet another situation that remains unhandled:
[GRP0:0]
migrator = TMIGR_NONE
active = NONE
groupmask = 1
/ \ \
0 1 2..7
idle idle idle
0) The system is fully idle.
[GRP0:0]
migrator = CPU 0
active = CPU 0
groupmask = 1
/ \ \
0 1 2..7
active idle idle
1) CPU 0 is activating. It has done the cmpxchg on the top's ->migr_state
but it hasn't yet returned to __walk_groups().
[GRP0:0]
migrator = CPU 0
active = CPU 0, CPU 1
groupmask = 1
/ \ \
0 1 2..7
active active idle
2) CPU 1 is activating. CPU 0 stays the migrator (still stuck in
__walk_groups(), delayed by #VMEXIT for example).
[GRP1:0]
migrator = TMIGR_NONE
active = NONE
groupmask = 1
/ \
[GRP0:0] [GRP0:1]
migrator = CPU 0 migrator = TMIGR_NONE
active = CPU 0, CPU1 active = NONE
groupmask = 1 groupmask = 2
/ \ \
0 1 2..7 8
active active idle !online
3) CPU 8 is preparing to boot. CPUHP_TMIGR_PREPARE is being ran by CPU 1
which has created the GRP0:1 and the new top GRP1:0 connected to GRP0:1
and GRP0:0. CPU 1 hasn't yet propagated its activation up to GRP1:0.
[GRP1:0]
migrator = GRP0:0
active = GRP0:0
groupmask = 1
/ \
[GRP0:0] [GRP0:1]
migrator = CPU 0 migrator = TMIGR_NONE
active = CPU 0, CPU1 active = NONE
groupmask = 1 groupmask = 2
/ \ \
0 1 2..7 8
active active idle !online
4) CPU 0 finally resumed after its #VMEXIT. It's in __walk_groups()
returning from tmigr_cpu_active(). The new top GRP1:0 is visible and
fetched and the pre-initialized groupmask of GRP0:0 is also visible.
As a result tmigr_active_up() is called to GRP1:0 with GRP0:0 as active
and migrator. CPU 0 is returning to __walk_groups() but suffers again
a #VMEXIT.
[GRP1:0]
migrator = GRP0:0
active = GRP0:0
groupmask = 1
/ \
[GRP0:0] [GRP0:1]
migrator = CPU 0 migrator = TMIGR_NONE
active = CPU 0, CPU1 active = NONE
groupmask = 1 groupmask = 2
/ \ \
0 1 2..7 8
active active idle !online
5) CPU 1 propagates its activation of GRP0:0 to GRP1:0. This has no
effect since CPU 0 did it already.
[GRP1:0]
migrator = GRP0:0
active = GRP0:0, GRP0:1
groupmask = 1
/ \
[GRP0:0] [GRP0:1]
migrator = CPU 0 migrator = CPU 8
active = CPU 0, CPU1 active = CPU 8
groupmask = 1 groupmask = 2
/ \ \ \
0 1 2..7 8
active active idle active
6) CPU 1 links CPU 8 to its group. CPU 8 boots and goes through
CPUHP_AP_TMIGR_ONLINE which propagates activation.
[GRP2:0]
migrator = TMIGR_NONE
active = NONE
groupmask = 1
/ \
[GRP1:0] [GRP1:1]
migrator = GRP0:0 migrator = TMIGR_NONE
active = GRP0:0, GRP0:1 active = NONE
groupmask = 1 groupmask = 2
/ \
[GRP0:0] [GRP0:1] [GRP0:2]
migrator = CPU 0 migrator = CPU 8 migrator = TMIGR_NONE
active = CPU 0, CPU1 active = CPU 8 active = NONE
groupmask = 1 groupmask = 2 groupmask = 0
/ \ \ \
0 1 2..7 8 64
active active idle active !online
7) CPU 64 is booting. CPUHP_TMIGR_PREPARE is being ran by CPU 1
which has created the GRP1:1, GRP0:2 and the new top GRP2:0 connected to
GRP1:1 and GRP1:0. CPU 1 hasn't yet propagated its activation up to
GRP2:0.
[GRP2:0]
migrator = 0 (!!!)
active = NONE
groupmask = 1
/ \
[GRP1:0] [GRP1:1]
migrator = GRP0:0 migrator = TMIGR_NONE
active = GRP0:0, GRP0:1 active = NONE
groupmask = 1 groupmask = 2
/ \
[GRP0:0] [GRP0:1] [GRP0:2]
migrator = CPU 0 migrator = CPU 8 migrator = TMIGR_NONE
active = CPU 0, CPU1 active = CPU 8 active = NONE
groupmask = 1 groupmask = 2 groupmask = 0
/ \ \ \
0 1 2..7 8 64
active active idle active !online
8) CPU 0 finally resumed after its #VMEXIT. It's in __walk_groups()
returning from tmigr_cpu_active(). The new top GRP2:0 is visible and
fetched but the pre-initialized groupmask of GRP1:0 is not because no
ordering made its initialization visible. As a result tmigr_active_up()
may be called to GRP2:0 with a "0" child's groumask. Leaving the timers
ignored for ever when the system is fully idle.
The race is highly theoretical and perhaps impossible in practice but
the groupmask of the child is not the only concern here as the whole
initialization of the child is not guaranteed to be visible to any
tree walker racing against hotplug (idle entry/exit, remote handling,
etc...). Although the current code layout seem to be resilient to such
hazards, this doesn't tell much about the future.
Fix this with enforcing address dependency between group initialization
and the write/read to the group's parent's pointer. Fortunately that
doesn't involve any barrier addition in the fast paths.
Fixes: 10a0e6f3d3db ("timers/migration: Move hierarchy setup into cpuhotplug prepare callback")
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20250114231507.21672-3-frederic@kernel.org
|
|
Commit 10a0e6f3d3db ("timers/migration: Move hierarchy setup into
cpuhotplug prepare callback") fixed a race between idle exit and CPU
hotplug up leading to a wrong "0" value migrator assigned to the top
level. However there is still a situation that remains unhandled:
[GRP0:0]
migrator = TMIGR_NONE
active = NONE
groupmask = 0
/ \ \
0 1 2..7
idle idle idle
0) The system is fully idle.
[GRP0:0]
migrator = CPU 0
active = CPU 0
groupmask = 0
/ \ \
0 1 2..7
active idle idle
1) CPU 0 is activating. It has done the cmpxchg on the top's ->migr_state
but it hasn't yet returned to __walk_groups().
[GRP0:0]
migrator = CPU 0
active = CPU 0, CPU 1
groupmask = 0
/ \ \
0 1 2..7
active active idle
2) CPU 1 is activating. CPU 0 stays the migrator (still stuck in
__walk_groups(), delayed by #VMEXIT for example).
[GRP1:0]
migrator = TMIGR_NONE
active = NONE
groupmask = 0
/ \
[GRP0:0] [GRP0:1]
migrator = CPU 0 migrator = TMIGR_NONE
active = CPU 0, CPU1 active = NONE
groupmask = 2 groupmask = 1
/ \ \
0 1 2..7 8
active active idle !online
3) CPU 8 is preparing to boot. CPUHP_TMIGR_PREPARE is being ran by CPU 1
which has created the GRP0:1 and the new top GRP1:0 connected to GRP0:1
and GRP0:0. The groupmask of GRP0:0 is now 2. CPU 1 hasn't yet
propagated its activation up to GRP1:0.
[GRP1:0]
migrator = 0 (!!!)
active = NONE
groupmask = 0
/ \
[GRP0:0] [GRP0:1]
migrator = CPU 0 migrator = TMIGR_NONE
active = CPU 0, CPU1 active = NONE
groupmask = 2 groupmask = 1
/ \ \
0 1 2..7 8
active active idle !online
4) CPU 0 finally resumed after its #VMEXIT. It's in __walk_groups()
returning from tmigr_cpu_active(). The new top GRP1:0 is visible and
fetched but the freshly updated groupmask of GRP0:0 may not be visible
due to lack of ordering! As a result tmigr_active_up() is called to
GRP0:0 with a child's groupmask of "0". This buggy "0" groupmask then
becomes the migrator for GRP1:0 forever. As a result, timers on a fully
idle system get ignored.
One possible fix would be to define TMIGR_NONE as "0" so that such a
race would have no effect. And after all TMIGR_NONE doesn't need to be
anything else. However this would leave an uncomfortable state machine
where gears happen not to break by chance but are vulnerable to future
modifications.
Keep TMIGR_NONE as is instead and pre-initialize to "1" the groupmask of
any newly created top level. This groupmask is guaranteed to be visible
upon fetching the corresponding group for the 1st time:
_ By the upcoming CPU thanks to CPU hotplug synchronization between the
control CPU (BP) and the booting one (AP).
_ By the control CPU since the groupmask and parent pointers are
initialized locally.
_ By all CPUs belonging to the same group than the control CPU because
they must wait for it to ever become idle before needing to walk to
the new top. The cmpcxhg() on ->migr_state then makes sure its
groupmask is visible.
With this pre-initialization, it is guaranteed that if a future top level
is linked to an old one, it is walked through with a valid groupmask.
Fixes: 10a0e6f3d3db ("timers/migration: Move hierarchy setup into cpuhotplug prepare callback")
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/all/20250114231507.21672-2-frederic@kernel.org
|
|
The recent conversion of brcmstb_l2_mask_and_ack() to
irq_gc_mask_disable_and_ack_set() missed that the driver can be built as a
module, but the generic function is not exported.
Add the missing export.
[ tglx: Converted it to a fix ]
Fixes: dd1f17a9faf5 ("irqchip/irq-brcmstb-l2: Replace brcmstb_l2_mask_and_ack() by generic function")
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250116005920.626822-1-linux@treblig.org
|
|
If a timer is deferrable and NO_HZ_COMMON is enabled, get_timer_cpu_base()
and get_timer_this_cpu_base() invoke per_cpu_ptr() and this_cpu_ptr()
twice.
While this seems to be cheap, get_timer_cpu_base() can be called in a loop
in lock_timer_base().
Optimize the functions by updating the base index for deferrable timers and
retrieving the actual base pointer once.
In both cases the resulting assembly code of those helpers becomes smaller,
which results in a ~30% execution time reduction for a lock_timer_base()
micro bench mark.
Signed-off-by: Zhongqiu Han <quic_zhonhan@quicinc.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/all/20241231150115.1978342-1-quic_zhonhan@quicinc.com
|
|
BPF programs can execute in all kinds of contexts and when a program
running in a non-preemptible context uses the bpf_send_signal() kfunc,
it will cause issues because this kfunc can sleep.
Change `irqs_disabled()` to `!preemptible()`.
Reported-by: syzbot+97da3d7e0112d59971de@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/67486b09.050a0220.253251.0084.GAE@google.com/
Fixes: 1bc7896e9ef4 ("bpf: Fix deadlock with rq_lock in bpf_send_signal()")
Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Acked-by: Yonghong Song <yonghong.song@linux.dev>
Link: https://lore.kernel.org/r/20250115103647.38487-1-puranjay@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
|
|
Add the description for @now to eliminate a kernel-doc warning.
timings.c:537: warning: Function parameter or struct member 'now' not described in 'irq_timings_next_event'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250111062954.910657-1-rdunlap@infradead.org
|
|
Now that x86 is converted over to use the IRQCHIP_MOVE_DEFERRED flags,
remove IRQ*_MOVE_PCNTXT and related code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241210103335.626707225@linutronix.de
|
|
ktime_get_fast_timestamps() was added in 2020 by commit e2d977c9f1ab
("timekeeping: Provide multi-timestamp accessor to NMI safe timekeeper")
but has remained unused.
Remove it.
[ tglx: Fold the inline as David suggested in the submission ]
Signed-off-by: Dr. David Alan Gilbert <linux@treblig.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250112160132.450209-1-linux@treblig.org
|
|
Use the correct kernel-doc notation for nested structs/unions to
eliminate warnings:
timer_migration.h:119: warning: Incorrect use of kernel-doc format: * struct - split state of tmigr_group
timer_migration.h:134: warning: Function parameter or struct member 'active' not described in 'tmigr_state'
timer_migration.h:134: warning: Function parameter or struct member 'migrator' not described in 'tmigr_state'
timer_migration.h:134: warning: Function parameter or struct member 'seq' not described in 'tmigr_state'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250111063156.910903-1-rdunlap@infradead.org
|
|
Add kernel-doc comments for two parameters to eliminate kernel-doc warnings:
tick-broadcast.c:1026: warning: Function parameter or struct member 'bc' not described in 'tick_broadcast_setup_oneshot'
tick-broadcast.c:1026: warning: Function parameter or struct member 'from_periodic' not described in 'tick_broadcast_setup_oneshot'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20250111063148.910887-1-rdunlap@infradead.org
|
|
The return type should be 'bool' instead of 'int' according to the calling
context in the kernel, and its internal implementation, i.e. :
return timerqueue_add();
which is a bool-return function.
[ tglx: Adjust function arguments ]
Signed-off-by: Richard Clark <richard.xnu.clark@gmail.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/Z2ppT7me13dtxm1a@MBC02GN1V4Q05P
|
|
When a pair of clocksource reads separated by a udelay(1) claim less than a
full microsecond of elapsed time, print the measured delay as part of the
splat.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/717a2ddf-a80f-490b-aa3a-4e4b74fa56ca@paulmck-laptop
|
|
The word 'accross' is wrong, so fix it.
Signed-off-by: Zhu Jun <zhujun2@cmss.chinamobile.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241204080907.11989-1-zhujun2@cmss.chinamobile.com
|
|
syzbot triggered the warning in posixtimer_send_sigqueue(), which warns
about a non-ignored signal being already queued on the ignored list.
The warning is actually bogus, as the following sequence causes this:
signal($SIG, SIGIGN);
timer_settime(...); // arm periodic timer
timer fires, signal is ignored and queued on ignored list
sigprocmask(SIG_BLOCK, ...); // block the signal
timer_settime(...); // re-arm periodic timer
timer fires, signal is not ignored because it is blocked
---> Warning triggers as signal is on the ignored list
Ideally timer_settime() could remove the signal, but that's racy and
incomplete vs. other scenarios and requires a full reevaluation of the
pending signal list.
Instead of adding more complexity, handle it gracefully by removing the
warning and requeueing the signal to the pending list. That's correct
versus:
1) sig[timed]wait() as that does not check for SIGIGN and only relies on
dequeue_signal() -> posixtimers_deliver_signal() to check whether the
pending signal is still valid.
2) Unblocking of the signal.
- If the unblocking happens before SIGIGN is replaced by a signal
handler, then the timer is rearmed in dequeue_signal(), but
get_signal() will ignore it. The next timer expiry will move it back
to the ignored list.
- If SIGIGN was replaced before unblocking, then the signal will be
delivered and a subsequent expiry will queue a signal on the pending
list again.
There is a related scenario to trigger the complementary warning in the
signal ignored path, which does not expect the signal to be on the pending
list when it is ignored. That can be triggered even before the above change
via:
task1 task2
signal($SIG, SIGIGN);
sigprocmask(SIG_BLOCK, ...);
timer_create(); // Signal target is task2
timer_settime(...); // arm periodic timer
timer fires, signal is not ignored because it is blocked
and queued on the pending list of task2
syscall()
// Sets the pending flag
sigprocmask(SIG_UNBLOCK, ...);
-> preemption, task2 cannot dequeue the signal
timer_settime(...); // re-arm periodic timer
timer fires, signal is ignored
---> Warning triggers as signal is on task2's pending list
and the thread group is not exiting
Consequently, remove that warning too and just keep the signal on the
pending list.
The following attempt to deliver the signal on return to user space of
task2 will ignore the signal and a subsequent expiry will bring it back to
the ignored list, if it did not get blocked or un-ignored before that.
Fixes: df7a996b4dab ("signal: Queue ignored posixtimers on ignore list")
Reported-by: syzbot+3c2e3cc60665d71de2f7@syzkaller.appspotmail.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Link: https://lore.kernel.org/all/87ikqhcnjn.ffs@tglx
|
|
The logic of GENERIC_PENDING_IRQ is backwards for historical reasons. Most
interrupt controllers allow to move the interrupt from arbitrary
contexts. If GENERIC_PENDING_IRQ is enabled by an architecture to support a
chip, which requires the affinity change to happen in interrupt context,
all other chips have to be marked with IRQF_MOVE_PCNTXT.
That's tedious and there is no real good reason for the extra flags in the
irq descriptor and the irq data status fields. In fact the decision whether
interrupts can be moved in arbitrary context or not is a property of the
interrupt chip.
To simplify adoption for RISC-V provide a new mechanism which is enabled
via a config switch and allows to add a flag to irq_chip::flags to request
that interrupt affinity changes are deferred. Setting the top level chip of
an interrupt evaluates the flag and maps it into the existing logic.
The config switch and the various PCNTXT flags are temporary until x86 is
converted over to this scheme. This intermediate step also allows trivial
backporting of the mechanism to plug the affinity change race of various
RISC-V interrupt controllers.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241210103335.500314436@linutronix.de
|
|
Now that it is unconditionally available, remove the wrapper.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241210101811.561078243@linutronix.de
|
|
Commit 1b57d91b969c ("irqchip/gic-v2, v3: Prevent SW resends entirely")
sett the flag which enforces interrupt handling in interrupt context and
prevents software base resends for ARM GIC v2/v3.
But it missed that the helper function which checks the flag was hidden
behind CONFIG_GENERIC_PENDING_IRQ, which is not set by ARM[64].
Make the helper unconditionally available so that the enforcement actually
works.
Fixes: 1b57d91b969c ("irqchip/gic-v2, v3: Prevent SW resends entirely")
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: https://lore.kernel.org/all/20241210101811.497716609@linutronix.de
|
|
During the dmem cgroup development, the parameters to the
dmem_cgroup_state_evict_valuable() and dmem_cgroup_try_charge() were
changed, but the documentation wasn't adjusted accordingly.
This results in a documentation build warning. Adjust the documentation
to reflect what the final functions parameters are.
Fixes: b168ed458dde ("kernel/cgroup: Add "dmem" memory accounting cgroup")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Closes: https://lore.kernel.org/r/20250113160334.1f09f881@canb.auug.org.au/
Acked-by: Tejun Heo <tj@kernel.org>
Reviewed-by: Simona Vetter <simona.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20250113092608.1349287-2-mripard@kernel.org
Signed-off-by: Maxime Ripard <mripard@kernel.org>
|
|
Variable climit is not effectively used, so delete it.
kernel/cgroup/dmem.c:302:23: warning: variable ‘climit’ set but not used.
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=13512
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Acked-by: Tejun Heo <tj@kernel.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20250114062804.5092-1-jiapeng.chong@linux.alibaba.com
Signed-off-by: Maxime Ripard <mripard@kernel.org>
|
|
Allow configuring the DPM watchdog to warn about slow suspend/resume
functions without causing a system panic(). This allows you to set the
DPM_WATCHDOG_WARNING_TIMEOUT to something like 5 or 10 seconds to get
warnings about slow suspend/resume functions that eventually succeed.
Signed-off-by: Douglas Anderson <dianders@chromium.org>
Reviewed-by: Tomasz Figa <tfiga@chromium.org>
Link: https://patch.msgid.link/20250109125957.v2.1.I4554f931b8da97948f308ecc651b124338ee9603@changeid
[ rjw: Subject edit ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
Modify a non-kernel-doc comment to begin with /* instead of /**
so that it does not cause a kernel-doc warning.
power.h:114: warning: This comment starts with '/**', but isn't a kernel-doc comment. Refer Documentation/doc-guide/kernel-doc.rst
* Auxiliary structure used for reading the snapshot image data and
power.h:114: warning: missing initial short description on line:
* Auxiliary structure used for reading the snapshot image data and
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Pavel Machek <pavel@ucw.cz>
Link: https://patch.msgid.link/20250111063107.910825-1-rdunlap@infradead.org
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
|
|
Print lazy preemption model in ftrace header when latency-format=1.
# cat /sys/kernel/debug/sched/preempt
none voluntary full (lazy)
Without patch:
latency: 0 us, #232946/232946, CPU#40 | (M:unknown VP:0, KP:0, SP:0 HP:0 #P:80)
^^^^^^^
With Patch:
latency: 0 us, #1897938/25566788, CPU#16 | (M:lazy VP:0, KP:0, SP:0 HP:0 #P:80)
^^^^
Now that lazy preemption is part of the kernel, make sure the tracing
infrastructure reflects that.
Link: https://lore.kernel.org/20250103093647.575919-1-sshegde@linux.ibm.com
Signed-off-by: Shrikanth Hegde <sshegde@linux.ibm.com>
Acked-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
The function graph tracer has become generic so that kretprobes and BPF
can use it along with function graph tracing itself. Some of the
infrastructure was specific for function graph tracing such as recording
the calltime and return time of the functions. Calling the clock code on a
high volume function does add overhead. The calculation of the calltime
was removed from the generic code and placed into the function graph
tracer itself so that the other users did not incur this overhead as they
did not need that timestamp.
The calltime field was still kept in the generic return entry structure
and the function graph return entry callback filled it as that structure
was passed to other code.
But this broke both irqsoff and wakeup latency tracer as they still
depended on the trace structure containing the calltime when the option
display-graph is set as it used some of those same functions that the
function graph tracer used. But now the calltime was not set and was just
zero. This caused the calculation of the function time to be the absolute
value of the return timestamp and not the length of the function.
# cd /sys/kernel/tracing
# echo 1 > options/display-graph
# echo irqsoff > current_tracer
The tracers went from:
# REL TIME CPU TASK/PID |||| DURATION FUNCTION CALLS
# | | | | |||| | | | | | |
0 us | 4) <idle>-0 | d..1. | 0.000 us | irqentry_enter();
3 us | 4) <idle>-0 | d..2. | | irq_enter_rcu() {
4 us | 4) <idle>-0 | d..2. | 0.431 us | preempt_count_add();
5 us | 4) <idle>-0 | d.h2. | | tick_irq_enter() {
5 us | 4) <idle>-0 | d.h2. | 0.433 us | tick_check_oneshot_broadcast_this_cpu();
6 us | 4) <idle>-0 | d.h2. | 2.426 us | ktime_get();
9 us | 4) <idle>-0 | d.h2. | | tick_nohz_stop_idle() {
10 us | 4) <idle>-0 | d.h2. | 0.398 us | nr_iowait_cpu();
11 us | 4) <idle>-0 | d.h1. | 1.903 us | }
11 us | 4) <idle>-0 | d.h2. | | tick_do_update_jiffies64() {
12 us | 4) <idle>-0 | d.h2. | | _raw_spin_lock() {
12 us | 4) <idle>-0 | d.h2. | 0.360 us | preempt_count_add();
13 us | 4) <idle>-0 | d.h3. | 0.354 us | do_raw_spin_lock();
14 us | 4) <idle>-0 | d.h2. | 2.207 us | }
15 us | 4) <idle>-0 | d.h3. | 0.428 us | calc_global_load();
16 us | 4) <idle>-0 | d.h3. | | _raw_spin_unlock() {
16 us | 4) <idle>-0 | d.h3. | 0.380 us | do_raw_spin_unlock();
17 us | 4) <idle>-0 | d.h3. | 0.334 us | preempt_count_sub();
18 us | 4) <idle>-0 | d.h1. | 1.768 us | }
18 us | 4) <idle>-0 | d.h2. | | update_wall_time() {
[..]
To:
# REL TIME CPU TASK/PID |||| DURATION FUNCTION CALLS
# | | | | |||| | | | | | |
0 us | 5) <idle>-0 | d.s2. | 0.000 us | _raw_spin_lock_irqsave();
0 us | 5) <idle>-0 | d.s3. | 312159583 us | preempt_count_add();
2 us | 5) <idle>-0 | d.s4. | 312159585 us | do_raw_spin_lock();
3 us | 5) <idle>-0 | d.s4. | | _raw_spin_unlock() {
3 us | 5) <idle>-0 | d.s4. | 312159586 us | do_raw_spin_unlock();
4 us | 5) <idle>-0 | d.s4. | 312159587 us | preempt_count_sub();
4 us | 5) <idle>-0 | d.s2. | 312159587 us | }
5 us | 5) <idle>-0 | d.s3. | | _raw_spin_lock() {
5 us | 5) <idle>-0 | d.s3. | 312159588 us | preempt_count_add();
6 us | 5) <idle>-0 | d.s4. | 312159589 us | do_raw_spin_lock();
7 us | 5) <idle>-0 | d.s3. | 312159590 us | }
8 us | 5) <idle>-0 | d.s4. | 312159591 us | calc_wheel_index();
9 us | 5) <idle>-0 | d.s4. | | enqueue_timer() {
9 us | 5) <idle>-0 | d.s4. | | wake_up_nohz_cpu() {
11 us | 5) <idle>-0 | d.s4. | | native_smp_send_reschedule() {
11 us | 5) <idle>-0 | d.s4. | 312171987 us | default_send_IPI_single_phys();
12408 us | 5) <idle>-0 | d.s3. | 312171990 us | }
12408 us | 5) <idle>-0 | d.s3. | 312171991 us | }
12409 us | 5) <idle>-0 | d.s3. | 312171991 us | }
Where the calculation of the time for each function was the return time
minus zero and not the time of when the function returned.
Have these tracers also save the calltime in the fgraph data section and
retrieve it again on the return to get the correct timings again.
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Link: https://lore.kernel.org/20250113183124.61767419@gandalf.local.home
Fixes: f1f36e22bee9 ("ftrace: Have calltime be saved in the fgraph storage")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
The KEXEC_JUMP flow is analogous to hibernation flows occurring before
and after creating an image and before and after jumping from the
restore kernel to the image one, which is why it uses the same device
callbacks as those hibernation flows.
Add comments explaining that to the code in question and update an
existing comment in it which appears a bit out of context.
No functional changes.
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Link: https://lore.kernel.org/r/20250109140757.2841269-8-dwmw2@infradead.org
|
|
Convert mm_lock_seq to be seqcount_t and change all mmap_write_lock
variants to increment it, in-line with the usual seqcount usage pattern.
This lets us check whether the mmap_lock is write-locked by checking
mm_lock_seq.sequence counter (odd=locked, even=unlocked). This will be
used when implementing mmap_lock speculation functions.
As a result vm_lock_seq is also change to be unsigned to match the type
of mm_lock_seq.sequence.
Link: https://lkml.kernel.org/r/20241122174416.1367052-2-surenb@google.com
Suggested-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.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: Hillf Danton <hdanton@sina.com>
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: 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: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Sourav Panda <souravpanda@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
CPU unplug first calls __cpu_disable(), and that's where powerpc calls
cleanup_cpu_mmu_context(), which clears this CPU from mm_cpumask() of all
mms in the system.
However this CPU may still be using a lazy tlb mm, and its mm_cpumask bit
will be cleared from it. The CPU does not switch away from the lazy tlb
mm until arch_cpu_idle_dead() calls idle_task_exit().
If that user mm exits in this window, it will not be subject to the lazy
tlb mm shootdown and may be freed while in use as a lazy mm by the CPU
that is being unplugged.
cleanup_cpu_mmu_context() could be moved later, but it looks better to
move the lazy tlb mm switching earlier. The problem with doing the lazy
mm switching in idle_task_exit() is explained in commit bf2c59fce4074
("sched/core: Fix illegal RCU from offline CPUs"), which added a wart to
switch away from the mm but leave it set in active_mm to be cleaned up
later.
So instead, switch away from the lazy tlb mm at sched_cpu_wait_empty(),
which is the last hotplug state before teardown
(CPUHP_AP_SCHED_WAIT_EMPTY). This CPU will never switch to a user thread
from this point, so it has no chance to pick up a new lazy tlb mm. This
removes the lazy tlb mm handling wart in CPU unplug.
With this, idle_task_exit() is not needed anymore and can be cleaned up.
This leaves the prototype alone, to be cleaned after this change.
herton: took the suggestions from https://lore.kernel.org/all/87jzvyprsw.ffs@tglx/
and made adjustments on the initial patch proposed by Nicholas.
Link: https://lkml.kernel.org/r/20230524060455.147699-1-npiggin@gmail.com
Link: https://lore.kernel.org/all/20230525205253.E2FAEC433EF@smtp.kernel.org/
Link: https://lkml.kernel.org/r/20241104142318.3295663-1-herton@redhat.com
Fixes: 2655421ae69f ("lazy tlb: shoot lazies, non-refcounting lazy tlb mm reference handling scheme")
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Herton R. Krzesinski <herton@redhat.com>
Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
kasan_record_aux_stack_noalloc() was introduced to record a stack trace
without allocating memory in the process. It has been added to callers
which were invoked while a raw_spinlock_t was held. More and more callers
were identified and changed over time. Is it a good thing to have this
while functions try their best to do a locklessly setup? The only
downside of having kasan_record_aux_stack() not allocate any memory is
that we end up without a stacktrace if stackdepot runs out of memory and
at the same stacktrace was not recorded before To quote Marco Elver from
https://lore.kernel.org/all/CANpmjNPmQYJ7pv1N3cuU8cP18u7PP_uoZD8YxwZd4jtbof9nVQ@mail.gmail.com/
| I'd be in favor, it simplifies things. And stack depot should be
| able to replenish its pool sufficiently in the "non-aux" cases
| i.e. regular allocations. Worst case we fail to record some
| aux stacks, but I think that's only really bad if there's a bug
| around one of these allocations. In general the probabilities
| of this being a regression are extremely small [...]
Make the kasan_record_aux_stack_noalloc() behaviour default as
kasan_record_aux_stack().
[bigeasy@linutronix.de: dressed the diff as patch]
Link: https://lkml.kernel.org/r/20241122155451.Mb2pmeyJ@linutronix.de
Fixes: 7cb3007ce2da ("kasan: generic: introduce kasan_record_aux_stack_noalloc()")
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reported-by: syzbot+39f85d612b7c20d8db48@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/67275485.050a0220.3c8d68.0a37.GAE@google.com
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Reviewed-by: Marco Elver <elver@google.com>
Reviewed-by: Waiman Long <longman@redhat.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Ben Segall <bsegall@google.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Frederic Weisbecker <frederic@kernel.org>
Cc: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: <kasan-dev@googlegroups.com>
Cc: Lai Jiangshan <jiangshanlai@gmail.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Neeraj Upadhyay <neeraj.upadhyay@kernel.org>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: syzkaller-bugs@googlegroups.com
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zqiang <qiang.zhang1211@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
In the loop of __rb_map_vma(), the 's' variable is calculated from the
same logic that nr_pages is and they both come from nr_subbufs. But the
relationship is not obvious and there's a WARN_ON_ONCE() around the 's'
variable to make sure it never becomes equal to nr_subbufs within the
loop. If that happens, then the code is buggy and needs to be fixed.
The 'page' variable is calculated from cpu_buffer->subbuf_ids[s] which is
an array of 'nr_subbufs' entries. If the code becomes buggy and 's'
becomes equal to or greater than 'nr_subbufs' then this will be an out of
bounds hit before the WARN_ON() is triggered and the code exiting safely.
Make the 'page' initialization consistent with the code logic and assign
it after the out of bounds check.
Link: https://lore.kernel.org/20250110162612.13983-1-aha310510@gmail.com
Signed-off-by: Jeongjun Park <aha310510@gmail.com>
[ sdr: rewrote change log ]
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
|
Currently there are two ways of identifying an empty ring-buffer. One
relying on the current status of the commit / reader page
(rb_per_cpu_empty()) and the other on the write and read counters
(rb_num_of_entries() used in rb_get_reader_page()).
with rb_num_of_entries(). This intends to ease later
introduction of ring-buffer writers which are out of the kernel control
and with whom, the only information available is through the meta-page
counters.
Link: https://lore.kernel.org/20250108114536.627715-2-vdonnefort@google.com
Signed-off-by: Vincent Donnefort <vdonnefort@google.com>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
|
