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author | Mikulas Patocka <mpatocka@redhat.com> | 2017-04-30 23:33:26 +0200 |
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committer | Mike Snitzer <snitzer@redhat.com> | 2017-05-01 21:18:13 +0200 |
commit | 1b0fb5a5b2dc0dddcfa575060441a7176ba7ac37 (patch) | |
tree | 7db34655122c059ee824083e4a682e229be2adc7 /drivers/md/Kconfig | |
parent | dm mpath: make it easier to detect unintended I/O request flushes (diff) | |
download | linux-1b0fb5a5b2dc0dddcfa575060441a7176ba7ac37.tar.xz linux-1b0fb5a5b2dc0dddcfa575060441a7176ba7ac37.zip |
dm bufio: avoid a possible ABBA deadlock
__get_memory_limit() tests if dm_bufio_cache_size changed and calls
__cache_size_refresh() if it did. It takes dm_bufio_clients_lock while
it already holds the client lock. However, lock ordering is violated
because in cleanup_old_buffers() dm_bufio_clients_lock is taken before
the client lock.
This results in a possible deadlock and lockdep engine warning.
Fix this deadlock by changing mutex_lock() to mutex_trylock(). If the
lock can't be taken, it will be re-checked next time when a new buffer
is allocated.
Also add "unlikely" to the if condition, so that the optimizer assumes
that the condition is false.
Cc: stable@vger.kernel.org
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Diffstat (limited to 'drivers/md/Kconfig')
0 files changed, 0 insertions, 0 deletions