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queue_attr_store() always freezes a device queue before calling the
attribute store operation. For attributes that control queue limits, the
store operation will also lock the queue limits with a call to
queue_limits_start_update(). However, some drivers (e.g. SCSI sd) may
need to issue commands to a device to obtain limit values from the
hardware with the queue limits locked. This creates a potential ABBA
deadlock situation if a user attempts to modify a limit (thus freezing
the device queue) while the device driver starts a revalidation of the
device queue limits.
Avoid such deadlock by not freezing the queue before calling the
->store_limit() method in struct queue_sysfs_entry and instead use the
queue_limits_commit_update_frozen helper to freeze the queue after taking
the limits lock.
This also removes taking the sysfs lock for the store_limit method as
it doesn't protect anything here, but creates even more nesting.
Hopefully it will go away from the actual sysfs methods entirely soon.
(commit log adapted from a similar patch from Damien Le Moal)
Fixes: ff956a3be95b ("block: use queue_limits_commit_update in queue_discard_max_store")
Fixes: 0327ca9d53bf ("block: use queue_limits_commit_update in queue_max_sectors_store")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250110054726.1499538-7-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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De-duplicate the code for updating queue limits by adding a store_limit
method that allows having common code handle the actual queue limits
update.
Note that this is a pure refactoring patch and does not address the
existing freeze vs limits lock order problem in the refactored code,
which will be addressed next.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20250110054726.1499538-6-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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When __blk_mq_update_nr_hw_queues changes the number of tag sets, it
might have to disable poll queues. Currently it does so by adjusting
the BLK_FEAT_POLL, which is a bit against the intent of features that
describe hardware / driver capabilities, but more importantly causes
nasty lock order problems with the broadly held freeze when updating the
number of hardware queues and the limits lock. Fix this by leaving
BLK_FEAT_POLL alone, and instead check for the number of poll queues in
the bio submission and poll handlers. While this adds extra work to the
fast path, the variables are in cache lines used by these operations
anyway, so it should be cheap enough.
Fixes: 8023e144f9d6 ("block: move the poll flag to queue_limits")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Link: https://lore.kernel.org/r/20250110054726.1499538-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Otherwise feature reconfiguration can race with I/O submission.
Also drop the bio_clear_polled in the error path, as the flag does not
matter for instant error completions, it is a left over from when we
allowed polled I/O to proceed unpolled in this case.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20250110054726.1499538-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add a helper that freezes the queue, updates the queue limits and
unfreezes the queue and convert all open coded versions of that to the
new helper.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250110054726.1499538-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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queue_limits_commit_update is the function that needs to operate on a
frozen queue, not queue_limits_start_update. Update the kerneldoc
comments to reflect that.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20250110054726.1499538-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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blkcg_fill_root_iostats() iterates over @block_class's devices by
class_dev_iter_(init|next)(), but does not end iterating with
class_dev_iter_exit(), so causes the class's subsystem refcount leakage.
Fix by ending the iterating with class_dev_iter_exit().
Fixes: ef45fe470e1e ("blk-cgroup: show global disk stats in root cgroup io.stat")
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: stable@vger.kernel.org
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Zijun Hu <quic_zijuhu@quicinc.com>
Link: https://lore.kernel.org/r/20250105-class_fix-v6-2-3a2f1768d4d4@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Our syzkaller report a following UAF for v6.6:
BUG: KASAN: slab-use-after-free in bfq_init_rq+0x175d/0x17a0 block/bfq-iosched.c:6958
Read of size 8 at addr ffff8881b57147d8 by task fsstress/232726
CPU: 2 PID: 232726 Comm: fsstress Not tainted 6.6.0-g3629d1885222 #39
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x91/0xf0 lib/dump_stack.c:106
print_address_description.constprop.0+0x66/0x300 mm/kasan/report.c:364
print_report+0x3e/0x70 mm/kasan/report.c:475
kasan_report+0xb8/0xf0 mm/kasan/report.c:588
hlist_add_head include/linux/list.h:1023 [inline]
bfq_init_rq+0x175d/0x17a0 block/bfq-iosched.c:6958
bfq_insert_request.isra.0+0xe8/0xa20 block/bfq-iosched.c:6271
bfq_insert_requests+0x27f/0x390 block/bfq-iosched.c:6323
blk_mq_insert_request+0x290/0x8f0 block/blk-mq.c:2660
blk_mq_submit_bio+0x1021/0x15e0 block/blk-mq.c:3143
__submit_bio+0xa0/0x6b0 block/blk-core.c:639
__submit_bio_noacct_mq block/blk-core.c:718 [inline]
submit_bio_noacct_nocheck+0x5b7/0x810 block/blk-core.c:747
submit_bio_noacct+0xca0/0x1990 block/blk-core.c:847
__ext4_read_bh fs/ext4/super.c:205 [inline]
ext4_read_bh+0x15e/0x2e0 fs/ext4/super.c:230
__read_extent_tree_block+0x304/0x6f0 fs/ext4/extents.c:567
ext4_find_extent+0x479/0xd20 fs/ext4/extents.c:947
ext4_ext_map_blocks+0x1a3/0x2680 fs/ext4/extents.c:4182
ext4_map_blocks+0x929/0x15a0 fs/ext4/inode.c:660
ext4_iomap_begin_report+0x298/0x480 fs/ext4/inode.c:3569
iomap_iter+0x3dd/0x1010 fs/iomap/iter.c:91
iomap_fiemap+0x1f4/0x360 fs/iomap/fiemap.c:80
ext4_fiemap+0x181/0x210 fs/ext4/extents.c:5051
ioctl_fiemap.isra.0+0x1b4/0x290 fs/ioctl.c:220
do_vfs_ioctl+0x31c/0x11a0 fs/ioctl.c:811
__do_sys_ioctl fs/ioctl.c:869 [inline]
__se_sys_ioctl+0xae/0x190 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x70/0x120 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x78/0xe2
Allocated by task 232719:
kasan_save_stack+0x22/0x50 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
__kasan_slab_alloc+0x87/0x90 mm/kasan/common.c:328
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook mm/slab.h:768 [inline]
slab_alloc_node mm/slub.c:3492 [inline]
kmem_cache_alloc_node+0x1b8/0x6f0 mm/slub.c:3537
bfq_get_queue+0x215/0x1f00 block/bfq-iosched.c:5869
bfq_get_bfqq_handle_split+0x167/0x5f0 block/bfq-iosched.c:6776
bfq_init_rq+0x13a4/0x17a0 block/bfq-iosched.c:6938
bfq_insert_request.isra.0+0xe8/0xa20 block/bfq-iosched.c:6271
bfq_insert_requests+0x27f/0x390 block/bfq-iosched.c:6323
blk_mq_insert_request+0x290/0x8f0 block/blk-mq.c:2660
blk_mq_submit_bio+0x1021/0x15e0 block/blk-mq.c:3143
__submit_bio+0xa0/0x6b0 block/blk-core.c:639
__submit_bio_noacct_mq block/blk-core.c:718 [inline]
submit_bio_noacct_nocheck+0x5b7/0x810 block/blk-core.c:747
submit_bio_noacct+0xca0/0x1990 block/blk-core.c:847
__ext4_read_bh fs/ext4/super.c:205 [inline]
ext4_read_bh_nowait+0x15a/0x240 fs/ext4/super.c:217
ext4_read_bh_lock+0xac/0xd0 fs/ext4/super.c:242
ext4_bread_batch+0x268/0x500 fs/ext4/inode.c:958
__ext4_find_entry+0x448/0x10f0 fs/ext4/namei.c:1671
ext4_lookup_entry fs/ext4/namei.c:1774 [inline]
ext4_lookup.part.0+0x359/0x6f0 fs/ext4/namei.c:1842
ext4_lookup+0x72/0x90 fs/ext4/namei.c:1839
__lookup_slow+0x257/0x480 fs/namei.c:1696
lookup_slow fs/namei.c:1713 [inline]
walk_component+0x454/0x5c0 fs/namei.c:2004
link_path_walk.part.0+0x773/0xda0 fs/namei.c:2331
link_path_walk fs/namei.c:3826 [inline]
path_openat+0x1b9/0x520 fs/namei.c:3826
do_filp_open+0x1b7/0x400 fs/namei.c:3857
do_sys_openat2+0x5dc/0x6e0 fs/open.c:1428
do_sys_open fs/open.c:1443 [inline]
__do_sys_openat fs/open.c:1459 [inline]
__se_sys_openat fs/open.c:1454 [inline]
__x64_sys_openat+0x148/0x200 fs/open.c:1454
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x70/0x120 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x78/0xe2
Freed by task 232726:
kasan_save_stack+0x22/0x50 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
kasan_save_free_info+0x2b/0x50 mm/kasan/generic.c:522
____kasan_slab_free mm/kasan/common.c:236 [inline]
__kasan_slab_free+0x12a/0x1b0 mm/kasan/common.c:244
kasan_slab_free include/linux/kasan.h:164 [inline]
slab_free_hook mm/slub.c:1827 [inline]
slab_free_freelist_hook mm/slub.c:1853 [inline]
slab_free mm/slub.c:3820 [inline]
kmem_cache_free+0x110/0x760 mm/slub.c:3842
bfq_put_queue+0x6a7/0xfb0 block/bfq-iosched.c:5428
bfq_forget_entity block/bfq-wf2q.c:634 [inline]
bfq_put_idle_entity+0x142/0x240 block/bfq-wf2q.c:645
bfq_forget_idle+0x189/0x1e0 block/bfq-wf2q.c:671
bfq_update_vtime block/bfq-wf2q.c:1280 [inline]
__bfq_lookup_next_entity block/bfq-wf2q.c:1374 [inline]
bfq_lookup_next_entity+0x350/0x480 block/bfq-wf2q.c:1433
bfq_update_next_in_service+0x1c0/0x4f0 block/bfq-wf2q.c:128
bfq_deactivate_entity+0x10a/0x240 block/bfq-wf2q.c:1188
bfq_deactivate_bfqq block/bfq-wf2q.c:1592 [inline]
bfq_del_bfqq_busy+0x2e8/0xad0 block/bfq-wf2q.c:1659
bfq_release_process_ref+0x1cc/0x220 block/bfq-iosched.c:3139
bfq_split_bfqq+0x481/0xdf0 block/bfq-iosched.c:6754
bfq_init_rq+0xf29/0x17a0 block/bfq-iosched.c:6934
bfq_insert_request.isra.0+0xe8/0xa20 block/bfq-iosched.c:6271
bfq_insert_requests+0x27f/0x390 block/bfq-iosched.c:6323
blk_mq_insert_request+0x290/0x8f0 block/blk-mq.c:2660
blk_mq_submit_bio+0x1021/0x15e0 block/blk-mq.c:3143
__submit_bio+0xa0/0x6b0 block/blk-core.c:639
__submit_bio_noacct_mq block/blk-core.c:718 [inline]
submit_bio_noacct_nocheck+0x5b7/0x810 block/blk-core.c:747
submit_bio_noacct+0xca0/0x1990 block/blk-core.c:847
__ext4_read_bh fs/ext4/super.c:205 [inline]
ext4_read_bh+0x15e/0x2e0 fs/ext4/super.c:230
__read_extent_tree_block+0x304/0x6f0 fs/ext4/extents.c:567
ext4_find_extent+0x479/0xd20 fs/ext4/extents.c:947
ext4_ext_map_blocks+0x1a3/0x2680 fs/ext4/extents.c:4182
ext4_map_blocks+0x929/0x15a0 fs/ext4/inode.c:660
ext4_iomap_begin_report+0x298/0x480 fs/ext4/inode.c:3569
iomap_iter+0x3dd/0x1010 fs/iomap/iter.c:91
iomap_fiemap+0x1f4/0x360 fs/iomap/fiemap.c:80
ext4_fiemap+0x181/0x210 fs/ext4/extents.c:5051
ioctl_fiemap.isra.0+0x1b4/0x290 fs/ioctl.c:220
do_vfs_ioctl+0x31c/0x11a0 fs/ioctl.c:811
__do_sys_ioctl fs/ioctl.c:869 [inline]
__se_sys_ioctl+0xae/0x190 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:51 [inline]
do_syscall_64+0x70/0x120 arch/x86/entry/common.c:81
entry_SYSCALL_64_after_hwframe+0x78/0xe2
commit 1ba0403ac644 ("block, bfq: fix uaf for accessing waker_bfqq after
splitting") fix the problem that if waker_bfqq is in the merge chain,
and current is the only procress, waker_bfqq can be freed from
bfq_split_bfqq(). However, the case that waker_bfqq is not in the merge
chain is missed, and if the procress reference of waker_bfqq is 0,
waker_bfqq can be freed as well.
Fix the problem by checking procress reference if waker_bfqq is not in
the merge_chain.
Fixes: 1ba0403ac644 ("block, bfq: fix uaf for accessing waker_bfqq after splitting")
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Yu Kuai <yukuai3@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20250108084148.1549973-1-yukuai1@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Use a plain BLK_MQ_F_* flag to select the round robin tag selection
instead of overlaying an enum with just two possible values into the
flags space.
Doing so allows adding a BLK_MQ_F_MAX sentinel for simplified overflow
checking in the messy debugfs helpers.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20250106083531.799976-5-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The only queues that really can't support a scheduler are those that
do not have a gendisk associated with them, and thus can't be used for
non-passthrough commands. In addition to those null_blk can optionally
set the flag, which is a bad odd. Replace the null_blk usage with
BLK_MQ_F_NO_SCHED_BY_DEFAULT to keep the expected semantics and then
remove BLK_MQ_F_NO_SCHED as the non-disk queues never call into
elevator_init_mq or blk_register_queue which adds the sysfs attributes.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250106083531.799976-4-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The little work done in blk_mq_init_bitmaps is easier done in the only
caller.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Link: https://lore.kernel.org/r/20250106083531.799976-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Add a big conditional for blk-mq vs not mq at the beginning of
add_disk_fwnode so that elevator_init_mq is only called for blk-mq disks,
and add checks that the right methods or set or not set based on the
queue type.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250106083531.799976-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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blk_rq_map_sg is maze of nested loops. Untangle it by creating an
iterator that returns [paddr,len] tuples for DMA mapping, and then
implement the DMA logic on top of this. This not only removes code
at the source level, but also generates nicer binary code:
$ size block/blk-merge.o.*
text data bss dec hex filename
10001 432 0 10433 28c1 block/blk-merge.o.new
10317 468 0 10785 2a21 block/blk-merge.o.old
Last but not least it will be used as a building block for a new
DMA mapping helper that doesn't rely on struct scatterlist.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20250106081609.798289-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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There is not real point in a helper just to assign three values to four
fields, especially when the surrounding code is working on the
neighbor fields directly.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Link: https://lore.kernel.org/r/20250103073417.459715-3-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Lift bio_split_rw_at into blk_rq_append_bio so that it validates the
hardware limits. With this all passthrough callers can simply add
bio_add_page to build the bio and delay checking for exceeding of limits
to this point instead of doing it for each page.
While this looks like adding a new expensive loop over all bio_vecs,
blk_rq_append_bio is already doing that just to counter the number of
segments.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Link: https://lore.kernel.org/r/20250103073417.459715-2-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Set kernel config:
CONFIG_BLK_DEV_LOOP=m
CONFIG_BLK_DEV_LOOP_MIN_COUNT=0
Do latter:
mknod loop0 b 7 0
exec 4<> loop0
Before commit e418de3abcda ("block: switch gendisk lookup to a simple
xarray"), lookup_gendisk will first use base_probe to load module loop,
and then the retry will call loop_probe to prepare the loop disk. Finally
open for this disk will success. However, after this commit, we lose the
retry logic, and open will fail with ENXIO. Block device autoloading is
deprecated and will be removed soon, but maybe we should keep open success
until we really remove it. So, give a retry to fix it.
Fixes: e418de3abcda ("block: switch gendisk lookup to a simple xarray")
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Yang Erkun <yangerkun@huawei.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241209110435.3670985-1-yangerkun@huaweicloud.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The elevator core now allows instances of 'struct elv_fs_entry' to be
moved into read-only memory. Make use of that to protect them against
accidental or malicious modifications.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20250102-sysfs-const-attr-elevator-v1-4-9837d2058c60@weissschuh.net
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The elevator core now allows instances of 'struct elv_fs_entry' to be
moved into read-only memory. Make use of that to protect them against
accidental or malicious modifications.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20250102-sysfs-const-attr-elevator-v1-3-9837d2058c60@weissschuh.net
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The elevator core now allows instances of 'struct elv_fs_entry' to be
moved into read-only memory. Make use of that to protect them against
accidental or malicious modifications.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20250102-sysfs-const-attr-elevator-v1-2-9837d2058c60@weissschuh.net
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The elevator core does not need to modify the sysfs attributes added by
the elevators. Reflect this in the types, so the attributes can be moved
into read-only memory.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://lore.kernel.org/r/20250102-sysfs-const-attr-elevator-v1-1-9837d2058c60@weissschuh.net
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Reduce the indentation level of the code in queue_zone_wplugs_show() by
moving the body of the loop in that function into a new function.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20241217210310.645966-5-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
For the blk_queue_exit() calls, document where the corresponding code can
be found that increases q->q_usage_counter.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20241217210310.645966-4-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Document which functions expect that their callers must hold a lock.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20241217210310.645966-3-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Only include those header files that are necessary.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20241217210310.645966-2-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
BLK_MQ_F_SHOULD_MERGE is set for all tag_sets except those that purely
process passthrough commands (bsg-lib, ufs tmf, various nvme admin
queues) and thus don't even check the flag. Remove it to simplify the
driver interface.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241219060214.1928848-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
There are no users left of the pci and virtio queue mapping helpers.
Thus remove them.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Daniel Wagner <wagi@kernel.org>
Link: https://lore.kernel.org/r/20241202-refactor-blk-affinity-helpers-v6-8-27211e9c2cd5@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
blk_mq_pci_map_queues and blk_mq_virtio_map_queues will create a CPU to
hardware queue mapping based on affinity information. These two function
share common code and only differ on how the affinity information is
retrieved. Also, those functions are located in the block subsystem
where it doesn't really fit in. They are virtio and pci subsystem
specific.
Thus introduce provide a generic mapping function which uses the
irq_get_affinity callback from bus_type.
Originally idea from Ming Lei <ming.lei@redhat.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Daniel Wagner <wagi@kernel.org>
Link: https://lore.kernel.org/r/20241202-refactor-blk-affinity-helpers-v6-4-27211e9c2cd5@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Now we only verify the outmost freeze & unfreeze in current context in case
that !q->mq_freeze_depth, so it is reliable to save queue lying state when
we want to lock the freeze queue since the state is one per-task variable
now.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241127135133.3952153-5-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Now blk_freeze_queue_start() can track disk state automatically, and
it isn't necessary to verify queue freeze manually in elevator_init_mq()
any more.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241127135133.3952153-4-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Now we only verify the outmost freeze & unfreeze in current context in case
that !q->mq_freeze_depth, so it is reliable to save disk DEAD state when
we want to lock the freeze queue since the state is one per-task variable
now.
Doing this way can kill lots of false positive when freeze queue is
called before adding disk[1].
[1] https://lore.kernel.org/linux-block/6741f6b2.050a0220.1cc393.0017.GAE@google.com/
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241127135133.3952153-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
The following check of 'q->mq_freeze_owner != current' covers the
previous one, so remove the unnecessary check.
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241127135133.3952153-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
If an iocb contains metadata, extract that and prepare the bip.
Based on flags specified by the user, set corresponding guard/app/ref
tags to be checked in bip.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20241128112240.8867-11-anuj20.g@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
This patch introduces BIP_CHECK_GUARD/REFTAG/APPTAG bip_flags which
indicate how the hardware should check the integrity payload.
BIP_CHECK_GUARD/REFTAG are conversion of existing semantics, while
BIP_CHECK_APPTAG is a new flag. The driver can now just rely on block
layer flags, and doesn't need to know the integrity source. Submitter
of PI decides which tags to check. This would also give us a unified
interface for user and kernel generated integrity.
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20241128112240.8867-8-anuj20.g@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
This patch refactors bio_integrity_map_user to accept iov_iter as
argument. This is a prep patch.
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Signed-off-by: Kanchan Joshi <joshi.k@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20241128112240.8867-4-anuj20.g@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Copy back the bounce buffer to user-space in entirety when the parent
bio completes. The existing code uses bip_iter.bi_size for sizing the
copy, which can be modified. So move away from that and fetch it from
the vector passed to the block layer. While at it, switch to using
better variable names.
Fixes: 492c5d455969f ("block: bio-integrity: directly map user buffers")
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20241128112240.8867-3-anuj20.g@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Introduce BIP_CLONE_FLAGS describing integrity flags that should be
inherited in the cloned bip from the parent.
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anuj Gupta <anuj20.g@samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Link: https://lore.kernel.org/r/20241128112240.8867-2-anuj20.g@samsung.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
If the 'hctx' isn't removed from cpuhp callback list, we can't reuse it,
otherwise use-after-free may be triggered.
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202412172217.b906db7c-lkp@intel.com
Tested-by: kernel test robot <oliver.sang@intel.com>
Fixes: 22465bbac53c ("blk-mq: move cpuhp callback registering out of q->sysfs_lock")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241218101617.3275704-3-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
acquiring sysfs_lock"
This reverts commit be26ba96421ab0a8fa2055ccf7db7832a13c44d2.
Commit be26ba96421a ("block: Fix potential deadlock while freezing queue and
acquiring sysfs_loc") actually reverts commit 22465bbac53c ("blk-mq: move cpuhp
callback registering out of q->sysfs_lock"), and causes the original resctrl
lockdep warning.
So revert it and we need to fix the issue in another way.
Cc: Nilay Shroff <nilay@linux.ibm.com>
Fixes: be26ba96421a ("block: Fix potential deadlock while freezing queue and acquiring sysfs_loc")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241218101617.3275704-2-ming.lei@redhat.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
We already have a helper for checking the limits on the block size
both low and high, just use that.
No functional changes.
Reviewed-by: John Garry <john.g.garry@oracle.com>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Keith Busch <kbusch@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241218020212.3657139-2-mcgrof@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
For storing a value to a queue attribute, the queue_attr_store function
first freezes the queue (->q_usage_counter(io)) and then acquire
->sysfs_lock. This seems not correct as the usual ordering should be to
acquire ->sysfs_lock before freezing the queue. This incorrect ordering
causes the following lockdep splat which we are able to reproduce always
simply by accessing /sys/kernel/debug file using ls command:
[ 57.597146] WARNING: possible circular locking dependency detected
[ 57.597154] 6.12.0-10553-gb86545e02e8c #20 Tainted: G W
[ 57.597162] ------------------------------------------------------
[ 57.597168] ls/4605 is trying to acquire lock:
[ 57.597176] c00000003eb56710 (&mm->mmap_lock){++++}-{4:4}, at: __might_fault+0x58/0xc0
[ 57.597200]
but task is already holding lock:
[ 57.597207] c0000018e27c6810 (&sb->s_type->i_mutex_key#3){++++}-{4:4}, at: iterate_dir+0x94/0x1d4
[ 57.597226]
which lock already depends on the new lock.
[ 57.597233]
the existing dependency chain (in reverse order) is:
[ 57.597241]
-> #5 (&sb->s_type->i_mutex_key#3){++++}-{4:4}:
[ 57.597255] down_write+0x6c/0x18c
[ 57.597264] start_creating+0xb4/0x24c
[ 57.597274] debugfs_create_dir+0x2c/0x1e8
[ 57.597283] blk_register_queue+0xec/0x294
[ 57.597292] add_disk_fwnode+0x2e4/0x548
[ 57.597302] brd_alloc+0x2c8/0x338
[ 57.597309] brd_init+0x100/0x178
[ 57.597317] do_one_initcall+0x88/0x3e4
[ 57.597326] kernel_init_freeable+0x3cc/0x6e0
[ 57.597334] kernel_init+0x34/0x1cc
[ 57.597342] ret_from_kernel_user_thread+0x14/0x1c
[ 57.597350]
-> #4 (&q->debugfs_mutex){+.+.}-{4:4}:
[ 57.597362] __mutex_lock+0xfc/0x12a0
[ 57.597370] blk_register_queue+0xd4/0x294
[ 57.597379] add_disk_fwnode+0x2e4/0x548
[ 57.597388] brd_alloc+0x2c8/0x338
[ 57.597395] brd_init+0x100/0x178
[ 57.597402] do_one_initcall+0x88/0x3e4
[ 57.597410] kernel_init_freeable+0x3cc/0x6e0
[ 57.597418] kernel_init+0x34/0x1cc
[ 57.597426] ret_from_kernel_user_thread+0x14/0x1c
[ 57.597434]
-> #3 (&q->sysfs_lock){+.+.}-{4:4}:
[ 57.597446] __mutex_lock+0xfc/0x12a0
[ 57.597454] queue_attr_store+0x9c/0x110
[ 57.597462] sysfs_kf_write+0x70/0xb0
[ 57.597471] kernfs_fop_write_iter+0x1b0/0x2ac
[ 57.597480] vfs_write+0x3dc/0x6e8
[ 57.597488] ksys_write+0x84/0x140
[ 57.597495] system_call_exception+0x130/0x360
[ 57.597504] system_call_common+0x160/0x2c4
[ 57.597516]
-> #2 (&q->q_usage_counter(io)#21){++++}-{0:0}:
[ 57.597530] __submit_bio+0x5ec/0x828
[ 57.597538] submit_bio_noacct_nocheck+0x1e4/0x4f0
[ 57.597547] iomap_readahead+0x2a0/0x448
[ 57.597556] xfs_vm_readahead+0x28/0x3c
[ 57.597564] read_pages+0x88/0x41c
[ 57.597571] page_cache_ra_unbounded+0x1ac/0x2d8
[ 57.597580] filemap_get_pages+0x188/0x984
[ 57.597588] filemap_read+0x13c/0x4bc
[ 57.597596] xfs_file_buffered_read+0x88/0x17c
[ 57.597605] xfs_file_read_iter+0xac/0x158
[ 57.597614] vfs_read+0x2d4/0x3b4
[ 57.597622] ksys_read+0x84/0x144
[ 57.597629] system_call_exception+0x130/0x360
[ 57.597637] system_call_common+0x160/0x2c4
[ 57.597647]
-> #1 (mapping.invalidate_lock#2){++++}-{4:4}:
[ 57.597661] down_read+0x6c/0x220
[ 57.597669] filemap_fault+0x870/0x100c
[ 57.597677] xfs_filemap_fault+0xc4/0x18c
[ 57.597684] __do_fault+0x64/0x164
[ 57.597693] __handle_mm_fault+0x1274/0x1dac
[ 57.597702] handle_mm_fault+0x248/0x484
[ 57.597711] ___do_page_fault+0x428/0xc0c
[ 57.597719] hash__do_page_fault+0x30/0x68
[ 57.597727] do_hash_fault+0x90/0x35c
[ 57.597736] data_access_common_virt+0x210/0x220
[ 57.597745] _copy_from_user+0xf8/0x19c
[ 57.597754] sel_write_load+0x178/0xd54
[ 57.597762] vfs_write+0x108/0x6e8
[ 57.597769] ksys_write+0x84/0x140
[ 57.597777] system_call_exception+0x130/0x360
[ 57.597785] system_call_common+0x160/0x2c4
[ 57.597794]
-> #0 (&mm->mmap_lock){++++}-{4:4}:
[ 57.597806] __lock_acquire+0x17cc/0x2330
[ 57.597814] lock_acquire+0x138/0x400
[ 57.597822] __might_fault+0x7c/0xc0
[ 57.597830] filldir64+0xe8/0x390
[ 57.597839] dcache_readdir+0x80/0x2d4
[ 57.597846] iterate_dir+0xd8/0x1d4
[ 57.597855] sys_getdents64+0x88/0x2d4
[ 57.597864] system_call_exception+0x130/0x360
[ 57.597872] system_call_common+0x160/0x2c4
[ 57.597881]
other info that might help us debug this:
[ 57.597888] Chain exists of:
&mm->mmap_lock --> &q->debugfs_mutex --> &sb->s_type->i_mutex_key#3
[ 57.597905] Possible unsafe locking scenario:
[ 57.597911] CPU0 CPU1
[ 57.597917] ---- ----
[ 57.597922] rlock(&sb->s_type->i_mutex_key#3);
[ 57.597932] lock(&q->debugfs_mutex);
[ 57.597940] lock(&sb->s_type->i_mutex_key#3);
[ 57.597950] rlock(&mm->mmap_lock);
[ 57.597958]
*** DEADLOCK ***
[ 57.597965] 2 locks held by ls/4605:
[ 57.597971] #0: c0000000137c12f8 (&f->f_pos_lock){+.+.}-{4:4}, at: fdget_pos+0xcc/0x154
[ 57.597989] #1: c0000018e27c6810 (&sb->s_type->i_mutex_key#3){++++}-{4:4}, at: iterate_dir+0x94/0x1d4
Prevent the above lockdep warning by acquiring ->sysfs_lock before
freezing the queue while storing a queue attribute in queue_attr_store
function. Later, we also found[1] another function __blk_mq_update_nr_
hw_queues where we first freeze queue and then acquire the ->sysfs_lock.
So we've also updated lock ordering in __blk_mq_update_nr_hw_queues
function and ensured that in all code paths we follow the correct lock
ordering i.e. acquire ->sysfs_lock before freezing the queue.
[1] https://lore.kernel.org/all/CAFj5m9Ke8+EHKQBs_Nk6hqd=LGXtk4mUxZUN5==ZcCjnZSBwHw@mail.gmail.com/
Reported-by: kjain@linux.ibm.com
Fixes: af2814149883 ("block: freeze the queue in queue_attr_store")
Tested-by: kjain@linux.ibm.com
Cc: hch@lst.de
Cc: axboe@kernel.dk
Cc: ritesh.list@gmail.com
Cc: ming.lei@redhat.com
Cc: gjoyce@linux.ibm.com
Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Link: https://lore.kernel.org/r/20241210144222.1066229-1-nilay@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Make queue_iostats_passthrough_show() report 0/1 in sysfs instead of 0/4.
This patch fixes the following sparse warning:
block/blk-sysfs.c:266:31: warning: incorrect type in argument 1 (different base types)
block/blk-sysfs.c:266:31: expected unsigned long var
block/blk-sysfs.c:266:31: got restricted blk_flags_t
Cc: Keith Busch <kbusch@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Fixes: 110234da18ab ("block: enable passthrough command statistics")
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20241212212941.1268662-4-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Move a statement that occurs in both branches of an if-statement in front
of the if-statement. Fix a typo in a source code comment. No functionality
has been changed.
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20241212212941.1268662-3-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
Since commit fde02699c242 ("block: mq-deadline: Remove support for zone
write locking"), the local variable 'insert_before' is assigned once and
is used once. Hence remove this local variable.
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Nitesh Shetty <nj.shetty@samsung.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20241212212941.1268662-2-bvanassche@acm.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
|
|
After a recent change to clamp() and its variants [1] that increases the
coverage of the check that high is greater than low because it can be
done through inlining, certain build configurations (such as s390
defconfig) fail to build with clang with:
block/blk-iocost.c:1101:11: error: call to '__compiletime_assert_557' declared with 'error' attribute: clamp() low limit 1 greater than high limit active
1101 | inuse = clamp_t(u32, inuse, 1, active);
| ^
include/linux/minmax.h:218:36: note: expanded from macro 'clamp_t'
218 | #define clamp_t(type, val, lo, hi) __careful_clamp(type, val, lo, hi)
| ^
include/linux/minmax.h:195:2: note: expanded from macro '__careful_clamp'
195 | __clamp_once(type, val, lo, hi, __UNIQUE_ID(v_), __UNIQUE_ID(l_), __UNIQUE_ID(h_))
| ^
include/linux/minmax.h:188:2: note: expanded from macro '__clamp_once'
188 | BUILD_BUG_ON_MSG(statically_true(ulo > uhi), \
| ^
__propagate_weights() is called with an active value of zero in
ioc_check_iocgs(), which results in the high value being less than the
low value, which is undefined because the value returned depends on the
order of the comparisons.
The purpose of this expression is to ensure inuse is not more than
active and at least 1. This could be written more simply with a ternary
expression that uses min(inuse, active) as the condition so that the
value of that condition can be used if it is not zero and one if it is.
Do this conversion to resolve the error and add a comment to deter
people from turning this back into clamp().
Fixes: 7caa47151ab2 ("blkcg: implement blk-iocost")
Link: https://lore.kernel.org/r/34d53778977747f19cce2abb287bb3e6@AcuMS.aculab.com/ [1]
Suggested-by: David Laight <david.laight@aculab.com>
Reported-by: Linux Kernel Functional Testing <lkft@linaro.org>
Closes: https://lore.kernel.org/llvm/CA+G9fYsD7mw13wredcZn0L-KBA3yeoVSTuxnss-AEWMN3ha0cA@mail.gmail.com/
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202412120322.3GfVe3vF-lkp@intel.com/
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Make bio_iov_bvec_set() accept a pointer to const iov_iter, which means
that we can drop the undesirable casting to struct iov_iter pointer in
blk_rq_map_user_bvec().
Signed-off-by: John Garry <john.g.garry@oracle.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20241202115727.2320401-1-john.g.garry@oracle.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Call bdev_offset_from_zone_start() instead of open-coding it.
Fixes: dd291d77cc90 ("block: Introduce zone write plugging")
Signed-off-by: LongPing Wei <weilongping@oppo.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20241107020439.1644577-1-weilongping@oppo.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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blkcg_unpin_online() walks up the blkcg hierarchy putting the online pin. To
walk up, it uses blkcg_parent(blkcg) but it was calling that after
blkcg_destroy_blkgs(blkcg) which could free the blkcg, leading to the
following UAF:
==================================================================
BUG: KASAN: slab-use-after-free in blkcg_unpin_online+0x15a/0x270
Read of size 8 at addr ffff8881057678c0 by task kworker/9:1/117
CPU: 9 UID: 0 PID: 117 Comm: kworker/9:1 Not tainted 6.13.0-rc1-work-00182-gb8f52214c61a-dirty #48
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS unknown 02/02/2022
Workqueue: cgwb_release cgwb_release_workfn
Call Trace:
<TASK>
dump_stack_lvl+0x27/0x80
print_report+0x151/0x710
kasan_report+0xc0/0x100
blkcg_unpin_online+0x15a/0x270
cgwb_release_workfn+0x194/0x480
process_scheduled_works+0x71b/0xe20
worker_thread+0x82a/0xbd0
kthread+0x242/0x2c0
ret_from_fork+0x33/0x70
ret_from_fork_asm+0x1a/0x30
</TASK>
...
Freed by task 1944:
kasan_save_track+0x2b/0x70
kasan_save_free_info+0x3c/0x50
__kasan_slab_free+0x33/0x50
kfree+0x10c/0x330
css_free_rwork_fn+0xe6/0xb30
process_scheduled_works+0x71b/0xe20
worker_thread+0x82a/0xbd0
kthread+0x242/0x2c0
ret_from_fork+0x33/0x70
ret_from_fork_asm+0x1a/0x30
Note that the UAF is not easy to trigger as the free path is indirected
behind a couple RCU grace periods and a work item execution. I could only
trigger it with artifical msleep() injected in blkcg_unpin_online().
Fix it by reading the parent pointer before destroying the blkcg's blkg's.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: Abagail ren <renzezhongucas@gmail.com>
Suggested-by: Linus Torvalds <torvalds@linuxfoundation.org>
Fixes: 4308a434e5e0 ("blkcg: don't offline parent blkcg first")
Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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Zone write plugging for handling writes to zones of a zoned block
device always execute a zone report whenever a write BIO to a zone
fails. The intent of this is to ensure that the tracking of a zone write
pointer is always correct to ensure that the alignment to a zone write
pointer of write BIOs can be checked on submission and that we can
always correctly emulate zone append operations using regular write
BIOs.
However, this error recovery scheme introduces a potential deadlock if a
device queue freeze is initiated while BIOs are still plugged in a zone
write plug and one of these write operation fails. In such case, the
disk zone write plug error recovery work is scheduled and executes a
report zone. This in turn can result in a request allocation in the
underlying driver to issue the report zones command to the device. But
with the device queue freeze already started, this allocation will
block, preventing the report zone execution and the continuation of the
processing of the plugged BIOs. As plugged BIOs hold a queue usage
reference, the queue freeze itself will never complete, resulting in a
deadlock.
Avoid this problem by completely removing from the zone write plugging
code the use of report zones operations after a failed write operation,
instead relying on the device user to either execute a report zones,
reset the zone, finish the zone, or give up writing to the device (which
is a fairly common pattern for file systems which degrade to read-only
after write failures). This is not an unreasonnable requirement as all
well-behaved applications, FSes and device mapper already use report
zones to recover from write errors whenever possible by comparing the
current position of a zone write pointer with what their assumption
about the position is.
The changes to remove the automatic error recovery are as follows:
- Completely remove the error recovery work and its associated
resources (zone write plug list head, disk error list, and disk
zone_wplugs_work work struct). This also removes the functions
disk_zone_wplug_set_error() and disk_zone_wplug_clear_error().
- Change the BLK_ZONE_WPLUG_ERROR zone write plug flag into
BLK_ZONE_WPLUG_NEED_WP_UPDATE. This new flag is set for a zone write
plug whenever a write opration targetting the zone of the zone write
plug fails. This flag indicates that the zone write pointer offset is
not reliable and that it must be updated when the next report zone,
reset zone, finish zone or disk revalidation is executed.
- Modify blk_zone_write_plug_bio_endio() to set the
BLK_ZONE_WPLUG_NEED_WP_UPDATE flag for the target zone of a failed
write BIO.
- Modify the function disk_zone_wplug_set_wp_offset() to clear this
new flag, thus implementing recovery of a correct write pointer
offset with the reset (all) zone and finish zone operations.
- Modify blkdev_report_zones() to always use the disk_report_zones_cb()
callback so that disk_zone_wplug_sync_wp_offset() can be called for
any zone marked with the BLK_ZONE_WPLUG_NEED_WP_UPDATE flag.
This implements recovery of a correct write pointer offset for zone
write plugs marked with BLK_ZONE_WPLUG_NEED_WP_UPDATE and within
the range of the report zones operation executed by the user.
- Modify blk_revalidate_seq_zone() to call
disk_zone_wplug_sync_wp_offset() for all sequential write required
zones when a zoned block device is revalidated, thus always resolving
any inconsistency between the write pointer offset of zone write
plugs and the actual write pointer position of sequential zones.
Fixes: dd291d77cc90 ("block: Introduce zone write plugging")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20241209122357.47838-5-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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The zone reclaim processing of the dm-zoned device mapper uses
blkdev_issue_zeroout() to align the write pointer of a zone being used
for reclaiming another zone, to write the valid data blocks from the
zone being reclaimed at the same position relative to the zone start in
the reclaim target zone.
The first call to blkdev_issue_zeroout() will try to use hardware
offload using a REQ_OP_WRITE_ZEROES operation if the device reports a
non-zero max_write_zeroes_sectors queue limit. If this operation fails
because of the lack of hardware support, blkdev_issue_zeroout() falls
back to using a regular write operation with the zero-page as buffer.
Currently, such REQ_OP_WRITE_ZEROES failure is automatically handled by
the block layer zone write plugging code which will execute a report
zones operation to ensure that the write pointer of the target zone of
the failed operation has not changed and to "rewind" the zone write
pointer offset of the target zone as it was advanced when the write zero
operation was submitted. So the REQ_OP_WRITE_ZEROES failure does not
cause any issue and blkdev_issue_zeroout() works as expected.
However, since the automatic recovery of zone write pointers by the zone
write plugging code can potentially cause deadlocks with queue freeze
operations, a different recovery must be implemented in preparation for
the removal of zone write plugging report zones based recovery.
Do this by introducing the new function blk_zone_issue_zeroout(). This
function first calls blkdev_issue_zeroout() with the flag
BLKDEV_ZERO_NOFALLBACK to intercept failures on the first execution
which attempt to use the device hardware offload with the
REQ_OP_WRITE_ZEROES operation. If this attempt fails, a report zone
operation is issued to restore the zone write pointer offset of the
target zone to the correct position and blkdev_issue_zeroout() is called
again without the BLKDEV_ZERO_NOFALLBACK flag. The report zones
operation performing this recovery is implemented using the helper
function disk_zone_sync_wp_offset() which calls the gendisk report_zones
file operation with the callback disk_report_zones_cb(). This callback
updates the target write pointer offset of the target zone using the new
function disk_zone_wplug_sync_wp_offset().
dmz_reclaim_align_wp() is modified to change its call to
blkdev_issue_zeroout() to a call to blk_zone_issue_zeroout() without any
other change needed as the two functions are functionnally equivalent.
Fixes: dd291d77cc90 ("block: Introduce zone write plugging")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Mike Snitzer <snitzer@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20241209122357.47838-4-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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There are currently any issuer of REQ_OP_ZONE_RESET and
REQ_OP_ZONE_FINISH operations that set REQ_NOWAIT. However, as we cannot
handle this flag correctly due to the potential request allocation
failure that may happen in blk_mq_submit_bio() after blk_zone_plug_bio()
has handled the zone write plug write pointer updates for the targeted
zones, modify blk_zone_wplug_handle_reset_or_finish() to warn if this
flag is set and ignore it.
Fixes: dd291d77cc90 ("block: Introduce zone write plugging")
Cc: stable@vger.kernel.org
Signed-off-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Link: https://lore.kernel.org/r/20241209122357.47838-3-dlemoal@kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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