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| author | Rafael J. Wysocki <rjw@sisk.pl> | 2012-01-29 20:35:52 +0100 |
|---|---|---|
| committer | Rafael J. Wysocki <rjw@sisk.pl> | 2012-01-29 20:35:52 +0100 |
| commit | 181e9bdef37bfcaa41f3ab6c948a2a0d60a268b5 (patch) | |
| tree | 66e69f83b63e8517a47e0eb0e7ae730d8a9a109b /kernel/power/user.c | |
| parent | 0a9626575400879d1d5e6bc8768188b938d7c501 (diff) | |
| download | lwn-181e9bdef37bfcaa41f3ab6c948a2a0d60a268b5.tar.gz lwn-181e9bdef37bfcaa41f3ab6c948a2a0d60a268b5.zip | |
PM / Hibernate: Fix s2disk regression related to freezing workqueues
Commit 2aede851ddf08666f68ffc17be446420e9d2a056
PM / Hibernate: Freeze kernel threads after preallocating memory
introduced a mechanism by which kernel threads were frozen after
the preallocation of hibernate image memory to avoid problems with
frozen kernel threads not responding to memory freeing requests.
However, it overlooked the s2disk code path in which the
SNAPSHOT_CREATE_IMAGE ioctl was run directly after SNAPSHOT_FREE,
which caused freeze_workqueues_begin() to BUG(), because it saw
that worqueues had been already frozen.
Although in principle this issue might be addressed by removing
the relevant BUG_ON() from freeze_workqueues_begin(), that would
reintroduce the very problem that commit 2aede851ddf08666f68ffc17be4
attempted to avoid into that particular code path. For this reason,
to fix the issue at hand, introduce thaw_kernel_threads() and make
the SNAPSHOT_FREE ioctl execute it.
Special thanks to Srivatsa S. Bhat for detailed analysis of the
problem.
Reported-and-tested-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: stable@kernel.org
Diffstat (limited to 'kernel/power/user.c')
| -rw-r--r-- | kernel/power/user.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/kernel/power/user.c b/kernel/power/user.c index 6b1ab7a88522..e5a21a857302 100644 --- a/kernel/power/user.c +++ b/kernel/power/user.c @@ -274,6 +274,15 @@ static long snapshot_ioctl(struct file *filp, unsigned int cmd, swsusp_free(); memset(&data->handle, 0, sizeof(struct snapshot_handle)); data->ready = 0; + /* + * It is necessary to thaw kernel threads here, because + * SNAPSHOT_CREATE_IMAGE may be invoked directly after + * SNAPSHOT_FREE. In that case, if kernel threads were not + * thawed, the preallocation of memory carried out by + * hibernation_snapshot() might run into problems (i.e. it + * might fail or even deadlock). + */ + thaw_kernel_threads(); break; case SNAPSHOT_PREF_IMAGE_SIZE: |