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authorMichael S. Tsirkin <[email protected]>2018-04-13 15:35:16 -0700
committerLinus Torvalds <[email protected]>2018-04-13 17:10:27 -0700
commit09e35a4a1ca8b9988ca9b8557d17948cd6c0808b (patch)
treedb4f2d25cac5066841c03f8e1cebdb55898d03df
parent60bb83b81169820c691fbfa33a6a4aef32aa4b0b (diff)
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. [[email protected]: simplification] Link: http://lkml.kernel.org/r/[email protected] Signed-off-by: Michael S. Tsirkin <[email protected]> Reviewed-by: Andrew Morton <[email protected]> Cc: Kirill A. Shutemov <[email protected]> Cc: Huang Ying <[email protected]> Cc: Jonathan Corbet <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Thorsten Leemhuis <[email protected]> Cc: <[email protected]> Signed-off-by: Andrew Morton <[email protected]> Signed-off-by: Linus Torvalds <[email protected]>
-rw-r--r--mm/gup_benchmark.c4
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/gup_benchmark.c b/mm/gup_benchmark.c
index 5c8e2abeaa15..0f44759486e2 100644
--- a/mm/gup_benchmark.c
+++ b/mm/gup_benchmark.c
@@ -23,7 +23,7 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
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;
@@ -41,6 +41,8 @@ static int __gup_benchmark_ioctl(unsigned int cmd,
}
nr = get_user_pages_fast(addr, nr, gup->flags & 1, pages + i);
+ if (nr <= 0)
+ break;
i += nr;
}
end_time = ktime_get();