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Message-Id: <20180417155751.942473855@linuxfoundation.org>
Date: Tue, 17 Apr 2018 17:58:17 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, "Michael S. Tsirkin" <mst@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Huang Ying <ying.huang@...el.com>,
Jonathan Corbet <corbet@....net>,
Peter Zijlstra <peterz@...radead.org>,
Thomas Gleixner <tglx@...utronix.de>,
Thorsten Leemhuis <regressions@...mhuis.info>,
Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 4.16 64/68] mm/gup_benchmark: handle gup failures
4.16-stable review patch. If anyone has any objections, please let me know.
------------------
From: Michael S. Tsirkin <mst@...hat.com>
commit 09e35a4a1ca8b9988ca9b8557d17948cd6c0808b upstream.
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.
[akpm@...ux-foundation.org: simplification]
Link: http://lkml.kernel.org/r/1522962072-182137-3-git-send-email-mst@redhat.com
Signed-off-by: Michael S. Tsirkin <mst@...hat.com>
Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>
Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Cc: Huang Ying <ying.huang@...el.com>
Cc: Jonathan Corbet <corbet@....net>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Thorsten Leemhuis <regressions@...mhuis.info>
Cc: <stable@...r.kernel.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
mm/gup_benchmark.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
--- a/mm/gup_benchmark.c
+++ b/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;
@@ -41,6 +41,8 @@ static int __gup_benchmark_ioctl(unsigne
}
nr = get_user_pages_fast(addr, nr, gup->flags & 1, pages + i);
+ if (nr <= 0)
+ break;
i += nr;
}
end_time = ktime_get();
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