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@google.com>
Link: https://lore.kernel.org/r/20220125051736.2981459-1-shakeelb@google.comSigned-off-by: Jens Axboe <axboe@kernel.dk>

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,