@@ -785,7 +785,7 @@ int hibernate(void)
unlock_device_hotplug();
if (snapshot_test) {
pm_pr_dbg("Checking hibernation image\n");
- error = swsusp_check();
+ error = swsusp_check(true);
if (!error)
error = load_image_and_restore();
}
@@ -983,7 +983,7 @@ static int software_resume(void)
MAJOR(swsusp_resume_device), MINOR(swsusp_resume_device));
pm_pr_dbg("Looking for hibernation image.\n");
- error = swsusp_check();
+ error = swsusp_check(false);
if (error)
goto Unlock;
@@ -173,7 +173,7 @@ extern int swsusp_swap_in_use(void);
#define SF_HW_SIG 8
/* kernel/power/hibernate.c */
-extern int swsusp_check(void);
+extern int swsusp_check(bool safe);
extern void swsusp_free(void);
extern int swsusp_read(unsigned int *flags_p);
extern int swsusp_write(unsigned int flags);
@@ -1514,13 +1514,17 @@ int swsusp_read(unsigned int *flags_p)
* swsusp_check - Check for swsusp signature in the resume device
*/
-int swsusp_check(void)
+int swsusp_check(bool safe)
{
+ fmode_t mode = FMODE_READ;
int error;
void *holder;
+ if (!safe)
+ mode |= FMODE_EXCL;
+
hib_resume_bdev = blkdev_get_by_dev(swsusp_resume_device,
- FMODE_READ | FMODE_EXCL, &holder);
+ mode, &holder);
if (!IS_ERR(hib_resume_bdev)) {
set_blocksize(hib_resume_bdev, PAGE_SIZE);
clear_page(swsusp_header);
@@ -1547,7 +1551,7 @@ int swsusp_check(void)
put:
if (error)
- blkdev_put(hib_resume_bdev, FMODE_READ | FMODE_EXCL);
+ blkdev_put(hib_resume_bdev, mode);
else
pr_debug("Image signature found, resuming\n");
} else {
The system refused to do a test_resume because it found that the swap device has already been taken by someone else. Specificly, the swsusp_check()->blkdev_get_by_dev(FMODE_EXCL) is supposed to do this check. Steps to reproduce: dd if=/dev/zero of=/swapfile bs=$(cat /proc/meminfo | awk '/MemTotal/ {print $2}') count=1024 conv=notrunc mkswap /swapfile swapon /swapfile swap-offset /swapfile echo 34816 > /sys/power/resume_offset echo test_resume > /sys/power/disk echo disk > /sys/power/state PM: Using 3 thread(s) for compression PM: Compressing and saving image data (293150 pages)... PM: Image saving progress: 0% PM: Image saving progress: 10% ata1: SATA link up 1.5 Gbps (SStatus 113 SControl 300) ata1.00: configured for UDMA/100 ata2: SATA link down (SStatus 0 SControl 300) ata5: SATA link down (SStatus 0 SControl 300) ata6: SATA link down (SStatus 0 SControl 300) ata3: SATA link down (SStatus 0 SControl 300) ata4: SATA link down (SStatus 0 SControl 300) PM: Image saving progress: 20% PM: Image saving progress: 30% PM: Image saving progress: 40% PM: Image saving progress: 50% pcieport 0000:00:02.5: pciehp: Slot(0-5): No device found PM: Image saving progress: 60% PM: Image saving progress: 70% PM: Image saving progress: 80% PM: Image saving progress: 90% PM: Image saving done PM: hibernation: Wrote 1172600 kbytes in 2.70 seconds (434.29 MB/s) PM: S| PM: hibernation: Basic memory bitmaps freed PM: Image not found (code -16) This is because when using the swapfile as the hibernation storage, the block device where the swapfile is located has already been mounted by the OS distribution(usually been mounted as the rootfs). This is not an issue for normal hibernation, because software_resume()->swsusp_check() happens before the block device(rootfs) mount. But it is a problem for the test_resume mode. Because when test_resume happens, the block device has been mounted already. Thus remove the FMODE_EXCL for test_resume mode. This would not be a problem because in test_resume stage, the processes have already been frozen, and the race condition described in Commit 39fbef4b0f77 ("PM: hibernate: Get block device exclusively in swsusp_check()") is unlikely to happen. Fixes: 39fbef4b0f77 ("PM: hibernate: Get block device exclusively in swsusp_check()") Reported-by: Yifan Li <yifan2.li@intel.com> Signed-off-by: Chen Yu <yu.c.chen@intel.com> --- kernel/power/hibernate.c | 4 ++-- kernel/power/power.h | 2 +- kernel/power/swap.c | 10 +++++++--- 3 files changed, 10 insertions(+), 6 deletions(-)