From 0d7c1153d9291197c1dc473cfaade77acb874b4b Mon Sep 17 00:00:00 2001 From: Alviro Iskandar Setiawan Date: Mon, 7 Feb 2022 21:05:33 +0700 Subject: [PATCH 1/2] io_uring: Clean up a false-positive warning from GCC 9.3.0 In io_recv(), if import_single_range() fails, the @flags variable is uninitialized, then it will goto out_free. After the goto, the compiler doesn't know that (ret < min_ret) is always true, so it thinks the "if ((flags & MSG_WAITALL) ..." path could be taken. The complaint comes from gcc-9 (Debian 9.3.0-22) 9.3.0: ``` fs/io_uring.c:5238 io_recvfrom() error: uninitialized symbol 'flags' ``` Fix this by bypassing the @ret and @flags check when import_single_range() fails. Reasons: 1. import_single_range() only returns -EFAULT when it fails. 2. At that point, @flags is uninitialized and shouldn't be read. Reported-by: kernel test robot Reported-by: Dan Carpenter Reported-by: "Chen, Rong A" Link: https://lore.gnuweeb.org/timl/d33bb5a9-8173-f65b-f653-51fc0681c6d6@intel.com/ Cc: Pavel Begunkov Suggested-by: Ammar Faizi Fixes: 7297ce3d59449de49d3c9e1f64ae25488750a1fc ("io_uring: improve send/recv error handling") Signed-off-by: Alviro Iskandar Setiawan Signed-off-by: Ammar Faizi Link: https://lore.kernel.org/r/20220207140533.565411-1-ammarfaizi2@gnuweeb.org Signed-off-by: Jens Axboe --- fs/io_uring.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 2e04f718319d..3445c4da0153 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -5228,7 +5228,6 @@ static int io_recv(struct io_kiocb *req, unsigned int issue_flags) min_ret = iov_iter_count(&msg.msg_iter); ret = sock_recvmsg(sock, &msg, flags); -out_free: if (ret < min_ret) { if (ret == -EAGAIN && force_nonblock) return -EAGAIN; @@ -5236,9 +5235,9 @@ out_free: ret = -EINTR; req_set_fail(req); } else if ((flags & MSG_WAITALL) && (msg.msg_flags & (MSG_TRUNC | MSG_CTRUNC))) { +out_free: req_set_fail(req); } - __io_req_complete(req, issue_flags, ret, io_put_kbuf(req)); return 0; } From 0a3f1e0beacf6cc8ae5f846b0641c1df476e83d6 Mon Sep 17 00:00:00 2001 From: Shakeel Butt Date: Mon, 24 Jan 2022 21:17:36 -0800 Subject: [PATCH 2/2] 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 Link: https://lore.kernel.org/r/20220125051736.2981459-1-shakeelb@google.com Signed-off-by: Jens Axboe --- 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 3445c4da0153..77b9c7e4793b 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -8932,10 +8932,9 @@ 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,