The patch titled
Subject: vfs: avoid softlockups with sendfile(2)
has been added to the -mm tree. Its filename is
vfs-avoid-softlockups-with-sendfile2.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/vfs-avoid-softlockups-with-sendfile2.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/vfs-avoid-softlockups-with-sendfile2.patch
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------------------------------------------------------
From: Jan Kara <jack@xxxxxxx>
Subject: vfs: avoid softlockups with sendfile(2)
The following test program from Dmitry can cause softlockups or RCU stalls
as it copies 1GB from tmpfs into eventfd and we don't have any scheduling
point at that path in sendfile(2) implementation:
int r1 = eventfd(0, 0);
int r2 = memfd_create("", 0);
unsigned long n = 1<<30;
fallocate(r2, 0, 0, n);
sendfile(r1, r2, 0, n);
Add cond_resched() into __splice_from_pipe() to fix the problem.
Signed-off-by: Jan Kara <jack@xxxxxxx>
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Tested-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/splice.c | 1 +
1 file changed, 1 insertion(+)
diff -puN fs/splice.c~vfs-avoid-softlockups-with-sendfile2 fs/splice.c
--- a/fs/splice.c~vfs-avoid-softlockups-with-sendfile2
+++ a/fs/splice.c
@@ -891,6 +891,7 @@ ssize_t __splice_from_pipe(struct pipe_i
splice_from_pipe_begin(sd);
do {
+ cond_resched();
ret = splice_from_pipe_next(pipe, sd);
if (ret > 0)
ret = splice_from_pipe_feed(pipe, sd, actor);
_
Patches currently in -mm which might be from jack@xxxxxxx are
vfs-make-sendfile2-killable-even-better.patch
vfs-avoid-softlockups-with-sendfile2.patch
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