diff options
| author | Khazhismel Kumykov <khazhy@chromium.org> | 2022-08-01 18:50:34 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2022-08-29 00:02:43 +0300 |
| commit | f87904c075515f3e1d8f4a7115869d3b914674fd (patch) | |
| tree | 311757d653b1ef1229b68692699e5b63949ba911 /mm | |
| parent | 9dfb3b8d655022760ca68af11821f1c63aa547c3 (diff) | |
| download | linux-f87904c075515f3e1d8f4a7115869d3b914674fd.tar.xz | |
writeback: avoid use-after-free after removing device
When a disk is removed, bdi_unregister gets called to stop further
writeback and wait for associated delayed work to complete. However,
wb_inode_writeback_end() may schedule bandwidth estimation dwork after
this has completed, which can result in the timer attempting to access the
just freed bdi_writeback.
Fix this by checking if the bdi_writeback is alive, similar to when
scheduling writeback work.
Since this requires wb->work_lock, and wb_inode_writeback_end() may get
called from interrupt, switch wb->work_lock to an irqsafe lock.
Link: https://lkml.kernel.org/r/20220801155034.3772543-1-khazhy@google.com
Fixes: 45a2966fd641 ("writeback: fix bandwidth estimate for spiky workload")
Signed-off-by: Khazhismel Kumykov <khazhy@google.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Cc: Michael Stapelberg <stapelberg+linux@google.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/backing-dev.c | 10 | ||||
| -rw-r--r-- | mm/page-writeback.c | 6 |
2 files changed, 10 insertions, 6 deletions
diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 95550b8fa7fe..de65cb1e5f76 100644 --- a/mm/backing-dev.c +++ b/mm/backing-dev.c @@ -260,10 +260,10 @@ void wb_wakeup_delayed(struct bdi_writeback *wb) unsigned long timeout; timeout = msecs_to_jiffies(dirty_writeback_interval * 10); - spin_lock_bh(&wb->work_lock); + spin_lock_irq(&wb->work_lock); if (test_bit(WB_registered, &wb->state)) queue_delayed_work(bdi_wq, &wb->dwork, timeout); - spin_unlock_bh(&wb->work_lock); + spin_unlock_irq(&wb->work_lock); } static void wb_update_bandwidth_workfn(struct work_struct *work) @@ -334,12 +334,12 @@ static void cgwb_remove_from_bdi_list(struct bdi_writeback *wb); static void wb_shutdown(struct bdi_writeback *wb) { /* Make sure nobody queues further work */ - spin_lock_bh(&wb->work_lock); + spin_lock_irq(&wb->work_lock); if (!test_and_clear_bit(WB_registered, &wb->state)) { - spin_unlock_bh(&wb->work_lock); + spin_unlock_irq(&wb->work_lock); return; } - spin_unlock_bh(&wb->work_lock); + spin_unlock_irq(&wb->work_lock); cgwb_remove_from_bdi_list(wb); /* diff --git a/mm/page-writeback.c b/mm/page-writeback.c index d0d466a5c804..032a7bf8d259 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -2892,6 +2892,7 @@ static void wb_inode_writeback_start(struct bdi_writeback *wb) static void wb_inode_writeback_end(struct bdi_writeback *wb) { + unsigned long flags; atomic_dec(&wb->writeback_inodes); /* * Make sure estimate of writeback throughput gets updated after @@ -2900,7 +2901,10 @@ static void wb_inode_writeback_end(struct bdi_writeback *wb) * that if multiple inodes end writeback at a similar time, they get * batched into one bandwidth update. */ - queue_delayed_work(bdi_wq, &wb->bw_dwork, BANDWIDTH_INTERVAL); + spin_lock_irqsave(&wb->work_lock, flags); + if (test_bit(WB_registered, &wb->state)) + queue_delayed_work(bdi_wq, &wb->bw_dwork, BANDWIDTH_INTERVAL); + spin_unlock_irqrestore(&wb->work_lock, flags); } bool __folio_end_writeback(struct folio *folio) |