From 6a0c7cd33075f6b7f1d80145bb19812beb3fc5c9 Mon Sep 17 00:00:00 2001 From: "Rafael J. Wysocki" Date: Thu, 14 Nov 2013 23:26:58 +0100 Subject: PM / Hibernate: Do not crash kernel in free_basic_memory_bitmaps() I have received a report about the BUG_ON() in free_basic_memory_bitmaps() triggering mysteriously during an aborted s2disk hibernation attempt. The only way I can explain that is that /dev/snapshot was first opened for writing (resume mode), then closed and then opened again for reading and closed again without freezing tasks. In that case the first invocation of snapshot_open() would set the free_bitmaps flag in snapshot_state, which is a static variable. That flag wouldn't be cleared later and the second invocation of snapshot_open() would just leave it like that, so the subsequent snapshot_release() would see data->frozen set and free_basic_memory_bitmaps() would be called unnecessarily. To prevent that from happening clear data->free_bitmaps in snapshot_open() when the file is being opened for reading (hibernate mode). In addition to that, replace the BUG_ON() in free_basic_memory_bitmaps() with a WARN_ON() as the kernel can continue just fine if the condition checked by that macro occurs. Fixes: aab172891542 (PM / hibernate: Fix user space driven resume regression) Reported-by: Oliver Lorenz Signed-off-by: Rafael J. Wysocki Cc: 3.12+ # 3.12+ --- kernel/power/snapshot.c | 3 ++- kernel/power/user.c | 1 + 2 files changed, 3 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/power/snapshot.c b/kernel/power/snapshot.c index 98c3b34a4cff..ac2d1f69490f 100644 --- a/kernel/power/snapshot.c +++ b/kernel/power/snapshot.c @@ -792,7 +792,8 @@ void free_basic_memory_bitmaps(void) { struct memory_bitmap *bm1, *bm2; - BUG_ON(!(forbidden_pages_map && free_pages_map)); + if (WARN_ON(!(forbidden_pages_map && free_pages_map))) + return; bm1 = forbidden_pages_map; bm2 = free_pages_map; diff --git a/kernel/power/user.c b/kernel/power/user.c index 957f06164ad1..ffc931c384ac 100644 --- a/kernel/power/user.c +++ b/kernel/power/user.c @@ -70,6 +70,7 @@ static int snapshot_open(struct inode *inode, struct file *filp) data->swap = swsusp_resume_device ? swap_type_of(swsusp_resume_device, 0, NULL) : -1; data->mode = O_RDONLY; + data->free_bitmaps = false; error = pm_notifier_call_chain(PM_HIBERNATION_PREPARE); if (error) pm_notifier_call_chain(PM_POST_HIBERNATION); -- cgit v1.2.1