Re: [PATCH 1/1] io_uring: more graceful request alloc OOM

[yang lan <lanyang0908@gmail.com>]

Hi,

Thanks for your response.

But I applied this patch to LTS kernel 5.10.180, it can still trigger this bug.

--- io_uring/io_uring.c.back    2023-05-20 17:11:25.870550438 +0800
+++ io_uring/io_uring.c 2023-05-20 16:35:24.265846283 +0800
@@ -1970,7 +1970,7 @@
static struct io_kiocb *io_alloc_req(struct io_ring_ctx *ctx)
        __must_hold(&ctx->uring_lock)
 {
        struct io_submit_state *state = &ctx->submit_state;
-       gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
+       gfp_t gfp = GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY;
        int ret, i;

        BUILD_BUG_ON(ARRAY_SIZE(state->reqs) < IO_REQ_ALLOC_BATCH);

The io_uring.c.back is the original file.
Do I apply this patch wrong?

Regards,

Yang

Pavel Begunkov <asml.silence@gmail.com> 于2023年5月19日周五 22:06写道：
>
> It's ok for io_uring request allocation to fail, however there are
> reports that it starts killing tasks instead of just returning back
> to the userspace. Add __GFP_NORETRY, so it doesn't trigger OOM killer.
>
> Cc: stable@vger.kernel.org
> Fixes: 2b188cc1bb857 ("Add io_uring IO interface")
> Reported-by: yang lan <lanyang0908@gmail.com>
> Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
> ---
>  io_uring/io_uring.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c
> index dab09f568294..ad34a4320dab 100644
> --- a/io_uring/io_uring.c
> +++ b/io_uring/io_uring.c
> @@ -1073,7 +1073,7 @@ static void io_flush_cached_locked_reqs(struct io_ring_ctx *ctx,
>  __cold bool __io_alloc_req_refill(struct io_ring_ctx *ctx)
>         __must_hold(&ctx->uring_lock)
>  {
> -       gfp_t gfp = GFP_KERNEL | __GFP_NOWARN;
> +       gfp_t gfp = GFP_KERNEL | __GFP_NOWARN | __GFP_NORETRY;
>         void *reqs[IO_REQ_ALLOC_BATCH];
>         int ret, i;
>
> --
> 2.40.0
>