Michal Hocko <mhocko@xxxxxxxxxx> writes:
> From: Michal Hocko <mhocko@xxxxxxxx>
>
> aio_setup_ring waits for mmap_sem in writable mode. If the waiting
> task gets killed by the oom killer it would block oom_reaper from
> asynchronous address space reclaim and reduce the chances of timely
> OOM resolving. Wait for the lock in the killable mode and return with
> EINTR if the task got killed while waiting. This will also expedite
> the return to the userspace and do_exit.
>
> Cc: Benjamin LaHaise <bcrl@xxxxxxxxx>
> Cc: Alexander Viro <viro@xxxxxxxxxxxxxxxxxx>
> Signed-off-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> fs/aio.c | 7 ++++++-
> 1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/fs/aio.c b/fs/aio.c
> index 56bcdf4105f4..1c2e7e2c1b2b 100644
> --- a/fs/aio.c
> +++ b/fs/aio.c
> @@ -520,7 +520,12 @@ static int aio_setup_ring(struct kioctx *ctx)
> ctx->mmap_size = nr_pages * PAGE_SIZE;
> pr_debug("attempting mmap of %lu bytes\n", ctx->mmap_size);
>
> - down_write(&mm->mmap_sem);
> + if (down_write_killable(&mm->mmap_sem)) {
> + ctx->mmap_size = 0;
> + aio_free_ring(ctx);
> + return -EINTR;
> + }
> +
> ctx->mmap_base = do_mmap_pgoff(ctx->aio_ring_file, 0, ctx->mmap_size,
> PROT_READ | PROT_WRITE,
> MAP_SHARED, 0, &unused);
Reviewed-by: Jeff Moyer <jmoyer@xxxxxxxxxx>
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