From 9466f43741bc08edd7b1bee642dd6f5561091634 Mon Sep 17 00:00:00 2001 From: Pavel Begunkov Date: Sat, 25 Jan 2020 22:34:01 +0300 Subject: [PATCH] io_uring: fix refcounting with batched allocations at OOM In case of out of memory the second argument of percpu_ref_put_many() in io_submit_sqes() may evaluate into "nr - (-EAGAIN)", that is clearly wrong. Fixes: 2b85edfc0c90 ("io_uring: batch getting pcpu references") Signed-off-by: Pavel Begunkov Signed-off-by: Jens Axboe --- fs/io_uring.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index a700ee5fc89d..1dd20305c664 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -4830,8 +4830,11 @@ static int io_submit_sqes(struct io_ring_ctx *ctx, unsigned int nr, break; } - if (submitted != nr) - percpu_ref_put_many(&ctx->refs, nr - submitted); + if (unlikely(submitted != nr)) { + int ref_used = (submitted == -EAGAIN) ? 0 : submitted; + + percpu_ref_put_many(&ctx->refs, nr - ref_used); + } if (link) io_queue_link_head(link); if (statep) -- 2.11.0