PM: hibernate: Do not get block device exclusively in test_resume mode

[ Upstream commit 5904de0d735bbb3b4afe9375c5b4f9748f882945 ]

The system refused to do a test_resume because it found that the
swap device has already been taken by someone else. Specifically,
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 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>
Suggested-by: Pavankumar Kondeti <quic_pkondeti@quicinc.com>
Tested-by: Pavankumar Kondeti <quic_pkondeti@quicinc.com>
Tested-by: Wendy Wang <wendy.wang@intel.com>
Signed-off-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/kernel/power/hibernate.c b/kernel/power/hibernate.c
index aa551b093c3f616bd72f966f68c7d78b3b44d9d3..30d1274f03f625b40c74274417096cd7b6ee7a53 100644 (file)
--- a/kernel/power/hibernate.c
+++ b/kernel/power/hibernate.c
@@ -688,18 +688,22 @@ static int load_image_and_restore(void)
 {
        int error;
        unsigned int flags;
+       fmode_t mode = FMODE_READ;
+
+       if (snapshot_test)
+               mode |= FMODE_EXCL;
 
        pm_pr_dbg("Loading hibernation image.\n");
 
        lock_device_hotplug();
        error = create_basic_memory_bitmaps();
        if (error) {
-               swsusp_close(FMODE_READ | FMODE_EXCL);
+               swsusp_close(mode);
                goto Unlock;
        }
 
        error = swsusp_read(&flags);
-       swsusp_close(FMODE_READ | FMODE_EXCL);
+       swsusp_close(mode);
        if (!error)
                error = hibernation_restore(flags & SF_PLATFORM_MODE);
 

diff --git a/kernel/power/swap.c b/kernel/power/swap.c
index 277434b6c0bfd24f4ff0d9c9c537322419f5d3b2..cc44c37699de689c05ef14d09514df434f1a40ab 100644 (file)
--- a/kernel/power/swap.c
+++ b/kernel/power/swap.c
@@ -1518,9 +1518,13 @@ int swsusp_check(void)
 {
        int error;
        void *holder;
+       fmode_t mode = FMODE_READ;
+
+       if (snapshot_test)
+               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 {