4.20-stable review patch. If anyone has any objections, please let me know.
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[ Upstream commit 848bd9acdcd00c164b42b14aacec242949ecd471 ]
The root cause is the race as follows: Thread #0 Thread #1
z_erofs_vle_unzip_kickoff z_erofs_submit_and_unzip
struct z_erofs_vle_unzip_io io[] atomic_add_return() wait_event() [end of function] wake_up()
Fix it by taking the waitqueue lock between atomic_add_return and wake_up to close such the race.
kernel message:
Unable to handle kernel paging request at virtual address 97f7052caa1303dc ... Workqueue: kverityd verity_work task: ffffffe32bcb8000 task.stack: ffffffe3298a0000 PC is at __wake_up_common+0x48/0xa8 LR is at __wake_up+0x3c/0x58 ... Call trace: ... [<ffffff94a08ff648>] __wake_up_common+0x48/0xa8 [<ffffff94a08ff8b8>] __wake_up+0x3c/0x58 [<ffffff94a0c11b60>] z_erofs_vle_unzip_kickoff+0x40/0x64 [<ffffff94a0c118e4>] z_erofs_vle_read_endio+0x94/0x134 [<ffffff94a0c83c9c>] bio_endio+0xe4/0xf8 [<ffffff94a1076540>] dec_pending+0x134/0x32c [<ffffff94a1076f28>] clone_endio+0x90/0xf4 [<ffffff94a0c83c9c>] bio_endio+0xe4/0xf8 [<ffffff94a1095024>] verity_work+0x210/0x368 [<ffffff94a08c4150>] process_one_work+0x188/0x4b4 [<ffffff94a08c45bc>] worker_thread+0x140/0x458 [<ffffff94a08cad48>] kthread+0xec/0x108 [<ffffff94a0883ab4>] ret_from_fork+0x10/0x1c Code: d1006273 54000260 f9400804 b9400019 (b85fc081) ---[ end trace be9dde154f677cd1 ]---
Reviewed-by: Chao Yu yuchao0@huawei.com Signed-off-by: Gao Xiang gaoxiang25@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/staging/erofs/unzip_vle.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/staging/erofs/unzip_vle.c b/drivers/staging/erofs/unzip_vle.c index 79d3ba62b298..45e88bada907 100644 --- a/drivers/staging/erofs/unzip_vle.c +++ b/drivers/staging/erofs/unzip_vle.c @@ -717,13 +717,18 @@ static void z_erofs_vle_unzip_kickoff(void *ptr, int bios) struct z_erofs_vle_unzip_io *io = tagptr_unfold_ptr(t); bool background = tagptr_unfold_tags(t);
- if (atomic_add_return(bios, &io->pending_bios)) + if (!background) { + unsigned long flags; + + spin_lock_irqsave(&io->u.wait.lock, flags); + if (!atomic_add_return(bios, &io->pending_bios)) + wake_up_locked(&io->u.wait); + spin_unlock_irqrestore(&io->u.wait.lock, flags); return; + }
- if (background) + if (!atomic_add_return(bios, &io->pending_bios)) queue_work(z_erofs_workqueue, &io->u.work); - else - wake_up(&io->u.wait); }
static inline void z_erofs_vle_read_endio(struct bio *bio)