linux-kernel - [PATCH] mm: io_uring: allow oom-killer from io_uring

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Message-Id: <20220125051736.2981459-1-shakeelb@google.com>
Date:   Mon, 24 Jan 2022 21:17:36 -0800
From:   Shakeel Butt <shakeelb@...gle.com>
To:     Jens Axboe <axboe@...nel.dk>,
        Pavel Begunkov <asml.silence@...il.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, io-uring@...r.kernel.org,
        Shakeel Butt <shakeelb@...gle.com>
Subject: [PATCH] mm: io_uring: allow oom-killer from io_uring_setup

On an overcommitted system which is running multiple workloads of
varying priorities, it is preferred to trigger an oom-killer to kill a
low priority workload than to let the high priority workload receiving
ENOMEMs. On our memory overcommitted systems, we are seeing a lot of
ENOMEMs instead of oom-kills because io_uring_setup callchain is using
__GFP_NORETRY gfp flag which avoids the oom-killer. Let's remove it and
allow the oom-killer to kill a lower priority job.

Signed-off-by: Shakeel Butt <shakeelb@...gle.com>
---
 fs/io_uring.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index e54c4127422e..d9eeb202363c 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -8928,10 +8928,9 @@ static void io_mem_free(void *ptr)
 
 static void *io_mem_alloc(size_t size)
 {
-	gfp_t gfp_flags = GFP_KERNEL | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP |
-				__GFP_NORETRY | __GFP_ACCOUNT;
+	gfp_t gfp = GFP_KERNEL_ACCOUNT | __GFP_ZERO | __GFP_NOWARN | __GFP_COMP;
 
-	return (void *) __get_free_pages(gfp_flags, get_order(size));
+	return (void *) __get_free_pages(gfp, get_order(size));
 }
 
 static unsigned long rings_size(unsigned sq_entries, unsigned cq_entries,
-- 
2.35.0.rc0.227.g00780c9af4-goog