diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2019-07-04 15:14:49 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-07-05 11:12:07 +0900 |
| commit | 8751853091998cd31e9e5f1e8206280155af8921 (patch) | |
| tree | 91fac9f6aa58ad6ec64d28413fdf2b2322afe096 | |
| parent | eef778c99c0239ed0a0696ddf22ae3673f28a489 (diff) | |
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: 0619317ff8baa2d ("block: add polled wakeup task helper")
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reported-by: Qian Cai <cai@lca.pw>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Jens Axboe <axboe@kernel.dk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/page_io.c | 13 |
1 files changed, 8 insertions, 5 deletions
diff --git a/mm/page_io.c b/mm/page_io.c index 189415852077..a39aac2f8c8d 100644 --- a/mm/page_io.c +++ b/mm/page_io.c @@ -137,8 +137,10 @@ out: unlock_page(page); WRITE_ONCE(bio->bi_private, NULL); bio_put(bio); - blk_wake_io_task(waiter); - put_task_struct(waiter); + if (waiter) { + blk_wake_io_task(waiter); + put_task_struct(waiter); + } } int generic_swapfile_activate(struct swap_info_struct *sis, @@ -395,11 +397,12 @@ int swap_readpage(struct page *page, bool synchronous) * Keep this task valid during swap readpage because the oom killer may * attempt to access it in the page fault retry time check. */ - get_task_struct(current); - bio->bi_private = current; bio_set_op_attrs(bio, REQ_OP_READ, 0); - if (synchronous) + if (synchronous) { bio->bi_opf |= REQ_HIPRI; + get_task_struct(current); + bio->bi_private = current; + } count_vm_event(PSWPIN); bio_get(bio); qc = submit_bio(bio); |