Hi Mikulas,
This seemed not issue on mainline, mutex in dm_bufio_shrink_count() had
been removed from mainline.
Thanks,
Junxiao.
On 8/8/19 2:50 AM, Mikulas Patocka wrote:
A deadlock with this stacktrace was observed.
The obvious problem here is that in the call chain
xfs_vm_direct_IO->__blockdev_direct_IO->do_blockdev_direct_IO->kmem_cache_alloc
we do a GFP_KERNEL allocation while we are in a filesystem driver and in a
block device driver.
This patch changes the direct-io code to use GFP_NOIO.
PID: 474 TASK: ffff8813e11f4600 CPU: 10 COMMAND: "kswapd0"
#0 [ffff8813dedfb938] __schedule at ffffffff8173f405
#1 [ffff8813dedfb990] schedule at ffffffff8173fa27
#2 [ffff8813dedfb9b0] schedule_timeout at ffffffff81742fec
#3 [ffff8813dedfba60] io_schedule_timeout at ffffffff8173f186
#4 [ffff8813dedfbaa0] bit_wait_io at ffffffff8174034f
#5 [ffff8813dedfbac0] __wait_on_bit at ffffffff8173fec8
#6 [ffff8813dedfbb10] out_of_line_wait_on_bit at ffffffff8173ff81
#7 [ffff8813dedfbb90] __make_buffer_clean at ffffffffa038736f [dm_bufio]
#8 [ffff8813dedfbbb0] __try_evict_buffer at ffffffffa0387bb8 [dm_bufio]
#9 [ffff8813dedfbbd0] dm_bufio_shrink_scan at ffffffffa0387cc3 [dm_bufio]
#10 [ffff8813dedfbc40] shrink_slab at ffffffff811a87ce
#11 [ffff8813dedfbd30] shrink_zone at ffffffff811ad778
#12 [ffff8813dedfbdc0] kswapd at ffffffff811ae92f
#13 [ffff8813dedfbec0] kthread at ffffffff810a8428
#14 [ffff8813dedfbf50] ret_from_fork at ffffffff81745242
PID: 14127 TASK: ffff881455749c00 CPU: 11 COMMAND: "loop1"
#0 [ffff88272f5af228] __schedule at ffffffff8173f405
#1 [ffff88272f5af280] schedule at ffffffff8173fa27
#2 [ffff88272f5af2a0] schedule_preempt_disabled at ffffffff8173fd5e
#3 [ffff88272f5af2b0] __mutex_lock_slowpath at ffffffff81741fb5
#4 [ffff88272f5af330] mutex_lock at ffffffff81742133
#5 [ffff88272f5af350] dm_bufio_shrink_count at ffffffffa03865f9 [dm_bufio]
#6 [ffff88272f5af380] shrink_slab at ffffffff811a86bd
#7 [ffff88272f5af470] shrink_zone at ffffffff811ad778
#8 [ffff88272f5af500] do_try_to_free_pages at ffffffff811adb34
#9 [ffff88272f5af590] try_to_free_pages at ffffffff811adef8
#10 [ffff88272f5af610] __alloc_pages_nodemask at ffffffff811a09c3
#11 [ffff88272f5af710] alloc_pages_current at ffffffff811e8b71
#12 [ffff88272f5af760] new_slab at ffffffff811f4523
#13 [ffff88272f5af7b0] __slab_alloc at ffffffff8173a1b5
#14 [ffff88272f5af880] kmem_cache_alloc at ffffffff811f484b
#15 [ffff88272f5af8d0] do_blockdev_direct_IO at ffffffff812535b3
#16 [ffff88272f5afb00] __blockdev_direct_IO at ffffffff81255dc3
#17 [ffff88272f5afb30] xfs_vm_direct_IO at ffffffffa01fe3fc [xfs]
#18 [ffff88272f5afb90] generic_file_read_iter at ffffffff81198994
#19 [ffff88272f5afc50] __dta_xfs_file_read_iter_2398 at ffffffffa020c970 [xfs]
#20 [ffff88272f5afcc0] lo_rw_aio at ffffffffa0377042 [loop]
#21 [ffff88272f5afd70] loop_queue_work at ffffffffa0377c3b [loop]
#22 [ffff88272f5afe60] kthread_worker_fn at ffffffff810a8a0c
#23 [ffff88272f5afec0] kthread at ffffffff810a8428
#24 [ffff88272f5aff50] ret_from_fork at ffffffff81745242
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx
---
fs/direct-io.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
Index: linux-2.6/fs/direct-io.c
===================================================================
--- linux-2.6.orig/fs/direct-io.c 2019-08-02 08:51:56.000000000 +0200
+++ linux-2.6/fs/direct-io.c 2019-08-08 11:22:18.000000000 +0200
@@ -436,7 +436,7 @@ dio_bio_alloc(struct dio *dio, struct di
* bio_alloc() is guaranteed to return a bio when allowed to sleep and
* we request a valid number of vectors.
*/
- bio = bio_alloc(GFP_KERNEL, nr_vecs);
+ bio = bio_alloc(GFP_NOIO, nr_vecs);
bio_set_dev(bio, bdev);
bio->bi_iter.bi_sector = first_sector;
@@ -1197,7 +1197,7 @@ do_blockdev_direct_IO(struct kiocb *iocb
if (iov_iter_rw(iter) == READ && !count)
return 0;
- dio = kmem_cache_alloc(dio_cache, GFP_KERNEL);
+ dio = kmem_cache_alloc(dio_cache, GFP_NOIO);
retval = -ENOMEM;
if (!dio)
goto out;
