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authorNikita Ermakov <sh1r4s3@mail.si-head.nl>2021-04-29 22:55:41 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-04-30 11:20:37 -0700
commitf6899bc03cbadc6e308d98252c4a832b5fd45b87 (patch)
tree047f88de9d3090eda8dd6ef962c4c8cf95c09aae /mm/msync.c
parent4b17f030fdc821ca58218489e3b7fd8381707849 (diff)
mm/msync: exit early when the flags is an MS_ASYNC and start < vm_start
If an unmapped region was found and the flag is MS_ASYNC (without MS_INVALIDATE) there is nothing to do and the result would be always -ENOMEM, so return immediately. Link: https://lkml.kernel.org/r/20201025092901.56399-1-sh1r4s3@mail.si-head.nl Signed-off-by: Nikita Ermakov <sh1r4s3@mail.si-head.nl> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/msync.c')
-rw-r--r--mm/msync.c6
1 files changed, 5 insertions, 1 deletions
diff --git a/mm/msync.c b/mm/msync.c
index 69c6d2029531..137d1c104f3e 100644
--- a/mm/msync.c
+++ b/mm/msync.c
@@ -55,7 +55,9 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags)
goto out;
/*
* If the interval [start,end) covers some unmapped address ranges,
- * just ignore them, but return -ENOMEM at the end.
+ * just ignore them, but return -ENOMEM at the end. Besides, if the
+ * flag is MS_ASYNC (w/o MS_INVALIDATE) the result would be -ENOMEM
+ * anyway and there is nothing left to do, so return immediately.
*/
mmap_read_lock(mm);
vma = find_vma(mm, start);
@@ -69,6 +71,8 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, len, int, flags)
goto out_unlock;
/* Here start < vma->vm_end. */
if (start < vma->vm_start) {
+ if (flags == MS_ASYNC)
+ goto out_unlock;
start = vma->vm_start;
if (start >= end)
goto out_unlock;