Subject: [merged] bdi-avoid-oops-on-device-removal.patch removed from -mm tree
To: jack@xxxxxxx,axboe@xxxxxxxxx,dbasehore@xxxxxxxxxxxx,stable@xxxxxxxxxxxxxxx,tj@xxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Fri, 04 Apr 2014 12:29:20 -0700
The patch titled
Subject: bdi: avoid oops on device removal
has been removed from the -mm tree. Its filename was
bdi-avoid-oops-on-device-removal.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Jan Kara <jack@xxxxxxx>
Subject: bdi: avoid oops on device removal
After 839a8e8660b67 ("writeback: replace custom worker pool implementation
with unbound workqueue") when device is removed while we are writing to it
we crash in bdi_writeback_workfn() -> set_worker_desc() because bdi->dev
is NULL. This can happen because even though bdi_unregister() cancels all
pending flushing work, nothing really prevents new ones from being queued
from balance_dirty_pages() or other places.
Fix the problem by clearing BDI_registered bit in bdi_unregister() and
checking it before scheduling of any flushing work.
Fixes: 839a8e8660b6777e7fe4e80af1a048aebe2b5977
Reviewed-by: Tejun Heo <tj@xxxxxxxxxx>
Signed-off-by: Jan Kara <jack@xxxxxxx>
Cc: Derek Basehore <dbasehore@xxxxxxxxxxxx>
Cc: Jens Axboe <axboe@xxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/fs-writeback.c | 23 ++++++++++++++++++-----
include/linux/backing-dev.h | 2 +-
mm/backing-dev.c | 13 +++++++++----
3 files changed, 28 insertions(+), 10 deletions(-)
diff -puN fs/fs-writeback.c~bdi-avoid-oops-on-device-removal fs/fs-writeback.c
--- a/fs/fs-writeback.c~bdi-avoid-oops-on-device-removal
+++ a/fs/fs-writeback.c
@@ -89,16 +89,29 @@ static inline struct inode *wb_inode(str
#define CREATE_TRACE_POINTS
#include <trace/events/writeback.h>
+static void bdi_wakeup_thread(struct backing_dev_info *bdi)
+{
+ spin_lock_bh(&bdi->wb_lock);
+ if (test_bit(BDI_registered, &bdi->state))
+ mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
+ spin_unlock_bh(&bdi->wb_lock);
+}
+
static void bdi_queue_work(struct backing_dev_info *bdi,
struct wb_writeback_work *work)
{
trace_writeback_queue(bdi, work);
spin_lock_bh(&bdi->wb_lock);
+ if (!test_bit(BDI_registered, &bdi->state)) {
+ if (work->done)
+ complete(work->done);
+ goto out_unlock;
+ }
list_add_tail(&work->list, &bdi->work_list);
- spin_unlock_bh(&bdi->wb_lock);
-
mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
+out_unlock:
+ spin_unlock_bh(&bdi->wb_lock);
}
static void
@@ -114,7 +127,7 @@ __bdi_start_writeback(struct backing_dev
work = kzalloc(sizeof(*work), GFP_ATOMIC);
if (!work) {
trace_writeback_nowork(bdi);
- mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
+ bdi_wakeup_thread(bdi);
return;
}
@@ -161,7 +174,7 @@ void bdi_start_background_writeback(stru
* writeback as soon as there is no other work to do.
*/
trace_writeback_wake_background(bdi);
- mod_delayed_work(bdi_wq, &bdi->wb.dwork, 0);
+ bdi_wakeup_thread(bdi);
}
/*
@@ -1017,7 +1030,7 @@ void bdi_writeback_workfn(struct work_st
current->flags |= PF_SWAPWRITE;
if (likely(!current_is_workqueue_rescuer() ||
- list_empty(&bdi->bdi_list))) {
+ !test_bit(BDI_registered, &bdi->state))) {
/*
* The normal path. Keep writing back @bdi until its
* work_list is empty. Note that this path is also taken
diff -puN include/linux/backing-dev.h~bdi-avoid-oops-on-device-removal include/linux/backing-dev.h
--- a/include/linux/backing-dev.h~bdi-avoid-oops-on-device-removal
+++ a/include/linux/backing-dev.h
@@ -95,7 +95,7 @@ struct backing_dev_info {
unsigned int max_ratio, max_prop_frac;
struct bdi_writeback wb; /* default writeback info for this bdi */
- spinlock_t wb_lock; /* protects work_list */
+ spinlock_t wb_lock; /* protects work_list & wb.dwork scheduling */
struct list_head work_list;
diff -puN mm/backing-dev.c~bdi-avoid-oops-on-device-removal mm/backing-dev.c
--- a/mm/backing-dev.c~bdi-avoid-oops-on-device-removal
+++ a/mm/backing-dev.c
@@ -297,7 +297,10 @@ void bdi_wakeup_thread_delayed(struct ba
unsigned long timeout;
timeout = msecs_to_jiffies(dirty_writeback_interval * 10);
- queue_delayed_work(bdi_wq, &bdi->wb.dwork, timeout);
+ spin_lock_bh(&bdi->wb_lock);
+ if (test_bit(BDI_registered, &bdi->state))
+ queue_delayed_work(bdi_wq, &bdi->wb.dwork, timeout);
+ spin_unlock_bh(&bdi->wb_lock);
}
/*
@@ -310,9 +313,6 @@ static void bdi_remove_from_list(struct
spin_unlock_bh(&bdi_lock);
synchronize_rcu_expedited();
-
- /* bdi_list is now unused, clear it to mark @bdi dying */
- INIT_LIST_HEAD(&bdi->bdi_list);
}
int bdi_register(struct backing_dev_info *bdi, struct device *parent,
@@ -363,6 +363,11 @@ static void bdi_wb_shutdown(struct backi
*/
bdi_remove_from_list(bdi);
+ /* Make sure nobody queues further work */
+ spin_lock_bh(&bdi->wb_lock);
+ clear_bit(BDI_registered, &bdi->state);
+ spin_unlock_bh(&bdi->wb_lock);
+
/*
* Drain work list and shutdown the delayed_work. At this point,
* @bdi->bdi_list is empty telling bdi_Writeback_workfn() that @bdi
_
Patches currently in -mm which might be from jack@xxxxxxx are
origin.patch
fs-mpagec-forgotten-write_sync-in-case-of-data-integrity-write.patch
linux-next.patch
mm-add-strictlimit-knob-v2.patch
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