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authorLinus Torvalds <torvalds@linux-foundation.org>2012-02-10 09:05:52 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-02-10 09:05:52 -0800
commitaf5feae3d7e821d8c4d38103a7f53146f2590892 (patch)
tree9017bb0661fb617177534f0617c3771d89e31afc /mm
parentce2814f227d3adae8456f7cbd0bd5f922fd284f0 (diff)
parent977b7e3a52a7421ad33a393a38ece59f3d41c2fa (diff)
downloadlinux-af5feae3d7e821d8c4d38103a7f53146f2590892.tar.gz
Merge tag 'writeback-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux
fix 1 mysterious divide error fix 3 NULL dereference bugs in writeback tracing, on SD card removal w/o umount * tag 'writeback-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux: writeback: fix dereferencing NULL bdi->dev on trace_writeback_queue lib: proportion: lower PROP_MAX_SHIFT to 32 on 64-bit kernel writeback: fix NULL bdi->dev in trace writeback_single_inode backing-dev: fix wakeup timer races with bdi_unregister()
Diffstat (limited to 'mm')
-rw-r--r--mm/backing-dev.c23
1 files changed, 18 insertions, 5 deletions
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 7ba8feae11b..dd8e2aafb07 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -318,7 +318,7 @@ static void wakeup_timer_fn(unsigned long data)
if (bdi->wb.task) {
trace_writeback_wake_thread(bdi);
wake_up_process(bdi->wb.task);
- } else {
+ } else if (bdi->dev) {
/*
* When bdi tasks are inactive for long time, they are killed.
* In this case we have to wake-up the forker thread which
@@ -584,6 +584,8 @@ EXPORT_SYMBOL(bdi_register_dev);
*/
static void bdi_wb_shutdown(struct backing_dev_info *bdi)
{
+ struct task_struct *task;
+
if (!bdi_cap_writeback_dirty(bdi))
return;
@@ -602,8 +604,13 @@ static void bdi_wb_shutdown(struct backing_dev_info *bdi)
* Finally, kill the kernel thread. We don't need to be RCU
* safe anymore, since the bdi is gone from visibility.
*/
- if (bdi->wb.task)
- kthread_stop(bdi->wb.task);
+ spin_lock_bh(&bdi->wb_lock);
+ task = bdi->wb.task;
+ bdi->wb.task = NULL;
+ spin_unlock_bh(&bdi->wb_lock);
+
+ if (task)
+ kthread_stop(task);
}
/*
@@ -623,7 +630,9 @@ static void bdi_prune_sb(struct backing_dev_info *bdi)
void bdi_unregister(struct backing_dev_info *bdi)
{
- if (bdi->dev) {
+ struct device *dev = bdi->dev;
+
+ if (dev) {
bdi_set_min_ratio(bdi, 0);
trace_writeback_bdi_unregister(bdi);
bdi_prune_sb(bdi);
@@ -632,8 +641,12 @@ void bdi_unregister(struct backing_dev_info *bdi)
if (!bdi_cap_flush_forker(bdi))
bdi_wb_shutdown(bdi);
bdi_debug_unregister(bdi);
- device_unregister(bdi->dev);
+
+ spin_lock_bh(&bdi->wb_lock);
bdi->dev = NULL;
+ spin_unlock_bh(&bdi->wb_lock);
+
+ device_unregister(dev);
}
}
EXPORT_SYMBOL(bdi_unregister);