mm/memory-failure.c: fix bug triggered by unpoisoning empty zero page
Injecting memory failure for page 0x19d0 at 0xb77d2000
MCE 0x19d0: non LRU page recovery: Ignored
MCE: Software-unpoisoned page 0x19d0
BUG: Bad page state in process bash pfn:019d0
page:f3461a00 count:0 mapcount:0 mapping: (null) index:0x0
page flags: 0x40000404(referenced|reserved)
Modules linked in: nfsd auth_rpcgss i915 nfs_acl nfs lockd video drm_kms_helper drm bnep rfcomm sunrpc bluetooth psmouse parport_pc ppdev lp serio_raw fscache parport gpio_ich lpc_ich mac_hid i2c_algo_bit tpm_tis wmi usb_storage hid_generic usbhid hid e1000e firewire_ohci firewire_core ahci ptp libahci pps_core crc_itu_t
CPU: 3 PID: 2123 Comm: bash Not tainted 3.11.0-rc6+ #12
Hardware name: LENOVO 7034DD7/ , BIOS 9HKT47AUS 01//2012
00000000 00000000 e9625ea0 c15ec49b f3461a00 e9625eb8 c15ea119 c17cbf18
ef084314 000019d0 f3461a00 e9625ed8 c110dc8a f3461a00 00000001 00000000
f3461a00 40000404 00000000 e9625ef8 c110dcc1 f3461a00 f3461a00 000019d0
Call Trace:
dump_stack+0x41/0x52
bad_page+0xcf/0xeb
free_pages_prepare+0x12a/0x140
free_hot_cold_page+0x21/0x110
__put_single_page+0x21/0x30
put_page+0x25/0x40
unpoison_memory+0x107/0x200
hwpoison_unpoison+0x20/0x30
simple_attr_write+0xb6/0xd0
vfs_write+0xa0/0x1b0
SyS_write+0x4f/0x90
sysenter_do_call+0x12/0x22
Disabling lock debugging due to kernel taint
Testcase:
#define _GNU_SOURCE
#include <stdlib.h>
#include <stdio.h>
#include <sys/mman.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <errno.h>
#define PAGES_TO_TEST 1
#define PAGE_SIZE 4096
int main(void)
{
char *mem;
mem = mmap(NULL, PAGES_TO_TEST * PAGE_SIZE,
PROT_READ | PROT_WRITE, MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
if (madvise(mem, PAGES_TO_TEST * PAGE_SIZE, MADV_HWPOISON) == -1)
return -1;
munmap(mem, PAGES_TO_TEST * PAGE_SIZE);
return 0;
}
There is one page reference count for default empty zero page,
madvise_hwpoison add another one by get_user_pages_fast. memory_hwpoison
reduce one page reference count since it's a non LRU page.
unpoison_memory release the last page reference count and free empty zero
page to buddy system which is not correct since empty zero page has
PG_reserved flag. This patch fix it by don't reduce the page reference
count under 1 against empty zero page.
Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index d04f990..d472e14 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -1388,7 +1388,7 @@
unlock_page(page);
put_page(page);
- if (freeit)
+ if (freeit && !(pfn == my_zero_pfn(0) && page_count(p) == 1))
put_page(page);
return 0;