]> git.ipfire.org Git - thirdparty/kernel/stable.git/commit
aoe: avoid potential deadlock at set_capacity
authorMaksim Kiselev <bigunclemax@gmail.com>
Wed, 24 Jan 2024 07:24:36 +0000 (10:24 +0300)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Thu, 17 Jul 2025 16:30:48 +0000 (18:30 +0200)
commit2499fa286fb010ceb289950050199f33c26667b9
tree7e3067c885e17a2320cd12d8777b2011d0947764
parent39d5137085a6c37ace4680ee4d24020a4a03e7dc
aoe: avoid potential deadlock at set_capacity

commit e169bd4fb2b36c4b2bee63c35c740c85daeb2e86 upstream.

Move set_capacity() outside of the section procected by (&d->lock).
To avoid possible interrupt unsafe locking scenario:

        CPU0                    CPU1
        ----                    ----
[1] lock(&bdev->bd_size_lock);
                                local_irq_disable();
                            [2] lock(&d->lock);
                            [3] lock(&bdev->bd_size_lock);
   <Interrupt>
[4]  lock(&d->lock);

  *** DEADLOCK ***

Where [1](&bdev->bd_size_lock) hold by zram_add()->set_capacity().
[2]lock(&d->lock) hold by aoeblk_gdalloc(). And aoeblk_gdalloc()
is trying to acquire [3](&bdev->bd_size_lock) at set_capacity() call.
In this situation an attempt to acquire [4]lock(&d->lock) from
aoecmd_cfg_rsp() will lead to deadlock.

So the simplest solution is breaking lock dependency
[2](&d->lock) -> [3](&bdev->bd_size_lock) by moving set_capacity()
outside.

Signed-off-by: Maksim Kiselev <bigunclemax@gmail.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/20240124072436.3745720-2-bigunclemax@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
[ Larry: backport to 5.15.y. Minor conflict resolved due to missing commit d9c2bd252a457
  aoe: add error handling support for add_disk() ]
Signed-off-by: Larry Bassel <larry.bassel@oracle.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/block/aoe/aoeblk.c