path: root/net
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authorNeilBrown <>2022-01-14 14:07:14 -0800
committerLinus Torvalds <>2022-01-15 16:30:29 +0200
commit4034247a0d6ab281ba3293798ce67af494d86129 (patch)
tree888a53c1c79490500c719b46894267e4f445264a /net
parent704687deaae768a818d7da0584ee021793a97684 (diff)
mm: introduce memalloc_retry_wait()
Various places in the kernel - largely in filesystems - respond to a memory allocation failure by looping around and re-trying. Some of these cannot conveniently use __GFP_NOFAIL, for reasons such as: - a GFP_ATOMIC allocation, which __GFP_NOFAIL doesn't work on - a need to check for the process being signalled between failures - the possibility that other recovery actions could be performed - the allocation is quite deep in support code, and passing down an extra flag to say if __GFP_NOFAIL is wanted would be clumsy. Many of these currently use congestion_wait() which (in almost all cases) simply waits the given timeout - congestion isn't tracked for most devices. It isn't clear what the best delay is for loops, but it is clear that the various filesystems shouldn't be responsible for choosing a timeout. This patch introduces memalloc_retry_wait() with takes on that responsibility. Code that wants to retry a memory allocation can call this function passing the GFP flags that were used. It will wait however is appropriate. For now, it only considers __GFP_NORETRY and whatever gfpflags_allow_blocking() tests. If blocking is allowed without __GFP_NORETRY, then alloc_page either made some reclaim progress, or waited for a while, before failing. So there is no need for much further waiting. memalloc_retry_wait() will wait until the current jiffie ends. If this condition is not met, then alloc_page() won't have waited much if at all. In that case memalloc_retry_wait() waits about 200ms. This is the delay that most current loops uses. linux/sched/mm.h needs to be included in some files now, but linux/backing-dev.h does not. Link: Signed-off-by: NeilBrown <> Cc: Dave Chinner <> Cc: Michal Hocko <> Cc: "Theodore Ts'o" <> Cc: Jaegeuk Kim <> Cc: Chao Yu <> Cc: Darrick J. Wong <> Cc: Chuck Lever <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'net')
1 files changed, 2 insertions, 1 deletions
diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c
index 1e99ba1b9d72..9cb18b822ab2 100644
--- a/net/sunrpc/svc_xprt.c
+++ b/net/sunrpc/svc_xprt.c
@@ -6,6 +6,7 @@
#include <linux/sched.h>
+#include <linux/sched/mm.h>
#include <linux/errno.h>
#include <linux/freezer.h>
#include <linux/kthread.h>
@@ -688,7 +689,7 @@ static int svc_alloc_arg(struct svc_rqst *rqstp)
return -EINTR;
- schedule_timeout(msecs_to_jiffies(500));
+ memalloc_retry_wait(GFP_KERNEL);
rqstp->rq_page_end = &rqstp->rq_pages[pages];
rqstp->rq_pages[pages] = NULL; /* this might be seen in nfsd_splice_actor() */