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Commit 87518530 authored by Oleg Nesterov's avatar Oleg Nesterov Committed by Linus Torvalds
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swap_readpage(): avoid blk_wake_io_task() if !synchronous

swap_readpage() sets waiter = bio->bi_private even if synchronous = F,
this means that the caller can get the spurious wakeup after return.

This can be fatal if blk_wake_io_task() does
set_current_state(TASK_RUNNING) after the caller does
set_special_state(), in the worst case the kernel can crash in
do_task_dead().

Link: http://lkml.kernel.org/r/20190704160301.GA5956@redhat.com


Fixes: 0619317f ("block: add polled wakeup task helper")
Signed-off-by: default avatarOleg Nesterov <oleg@redhat.com>
Reported-by: default avatarQian Cai <cai@lca.pw>
Acked-by: default avatarHugh Dickins <hughd@google.com>
Reviewed-by: default avatarJens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent eef778c9
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