The patch titled
Subject: mm/gup_benchmark: handle gup failures
has been added to the -mm tree. Its filename is
mm-gup_benchmark-handle-gup-failures.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-gup_benchmark-handle-gup-failures.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-gup_benchmark-handle-gup-failures.patch
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------------------------------------------------------
From: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
Subject: mm/gup_benchmark: handle gup failures
Patch series "mm/get_user_pages_fast fixes, cleanups", v2.
Turns out get_user_pages_fast and __get_user_pages_fast return different
values on error when given a single page: __get_user_pages_fast returns 0.
get_user_pages_fast returns either 0 or an error.
Callers of get_user_pages_fast expect an error so fix it up to return an
error consistently.
Stress the difference between get_user_pages_fast and
__get_user_pages_fast to make sure callers aren't confused.
This patch (of 3):
__gup_benchmark_ioctl does not handle the case where get_user_pages_fast
fails:
- a negative return code will cause a buffer overrun
- returning with partial success will cause use of
uninitialized memory.
Link: http://lkml.kernel.org/r/1522962072-182137-3-git-send-email-mst@xxxxxxxxxx
Signed-off-by: Michael S. Tsirkin <mst@xxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Thorsten Leemhuis <regressions@xxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
diff -puN mm/gup_benchmark.c~mm-gup_benchmark-handle-gup-failures mm/gup_benchmark.c
--- a/mm/gup_benchmark.c~mm-gup_benchmark-handle-gup-failures
+++ a/mm/gup_benchmark.c
@@ -23,7 +23,7 @@ static int __gup_benchmark_ioctl(unsigne
struct page **pages;
nr_pages = gup->size / PAGE_SIZE;
- pages = kvmalloc(sizeof(void *) * nr_pages, GFP_KERNEL);
+ pages = kvzalloc(sizeof(void *) * nr_pages, GFP_KERNEL);
if (!pages)
return -ENOMEM;
@@ -41,7 +41,8 @@ static int __gup_benchmark_ioctl(unsigne
}
nr = get_user_pages_fast(addr, nr, gup->flags & 1, pages + i);
- i += nr;
+ if (nr > 0)
+ i += nr;
}
end_time = ktime_get();
_
Patches currently in -mm which might be from mst@xxxxxxxxxx are
mm-gup_benchmark-handle-gup-failures.patch
gup-return-efault-on-access_ok-failure.patch
mm-gup-document-return-value.patch