>From e20cd50a8f612dbc720d31d269e748215607a0b8 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Date: Fri, 29 Jan 2016 14:55:40 +0300
Subject: [PATCH 1/2] mm: fix bogus VM_BUG_ON_PAGE() in isolate_lru_page()
We don't care if there's a tail pages which is not on LRU. We are not
going to isolate them anyway.
Testcase:
#include <fcntl.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/mman.h>
#include <numaif.h>
#define SIZE 0x2000
int foo;
int main()
{
int fd;
char *p;
unsigned long mask = 2;
fd = open("/dev/sg0", O_RDWR);
p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
/* Faultin pages */
foo = p[0] + p[0x1000];
mbind(p, SIZE, MPOL_BIND, &mask, 4, MPOL_MF_MOVE | MPOL_MF_STRICT);
return 0;
}
MPOL_MF_STRICT makes queue_pages_test_walk() ignore !vma_megratable()
and we try to queue such pages for migration. It's good question why we
ignore !vma_megratable() for MPOL_MF_STRICT, but it's subject for a
separate patch.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Fixes: bb5b8589767a ("mm: make sure isolate_lru_page() is never called for tail page")
---
mm/vmscan.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index eb3dd37ccd7c..492fbe73420b 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1443,7 +1443,7 @@ int isolate_lru_page(struct page *page)
int ret = -EBUSY;
VM_BUG_ON_PAGE(!page_count(page), page);
- VM_BUG_ON_PAGE(PageTail(page), page);
+ VM_BUG_ON_PAGE(PageLRU(page) && PageTail(page), page);
if (PageLRU(page)) {
struct zone *zone = page_zone(page);
--
2.7.0.rc3
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