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ANDROID: mm: page_pinner: unattribute follow_page in munlock_vma_pages_range

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munlock_vma_pages_range uses follow_page(FOLL_GET) so we need to use
put_user_page to avoid false positive. However, munlock path is quite
complicated to attribute them. At this point, do not make the muck.
Instead just unattribute them to avoid false positive.

Bug: 183414571
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Minchan Kim <minchan@google.com>
Change-Id: I4776bd1a94247e226b29fceb3879c338e8c7323a
This commit is contained in:
Minchan Kim 2021-03-23 10:28:47 -07:00 committed by Minchan Kim
parent ec1dbc10ad
commit c2b7c24bc1
1 changed files with 9 additions and 1 deletions
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10
mm/mlock.c
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@ -17,6 +17,7 @@
#include <linux/mempolicy.h>
#include <linux/syscalls.h>
#include <linux/sched.h>
#include <linux/page_pinner.h>
#include <linux/export.h>
#include <linux/rmap.h>
#include <linux/mmzone.h>
@ -470,8 +471,15 @@ void munlock_vma_pages_range(struct vm_area_struct *vma,
* has sneaked into the range, we won't oops here: great).
*/
page = follow_page(vma, start, FOLL_GET | FOLL_DUMP);
if (page && !IS_ERR(page)) {
/*
* munlock_vma_pages_range uses follow_page(FOLL_GET)
* so it need to use put_user_page but the munlock
* path is quite complicated to deal with each put
* sites correctly so just unattribute them to avoid
* false positive at this moment.
*/
reset_page_pinner(page, compound_order(page));
if (PageTransTail(page)) {
VM_BUG_ON_PAGE(PageMlocked(page), page);
put_page(page); /* follow_page_mask() */