Commits
Jens Axboe committed 61cce6f6eec
scsi: sd: use mempool for discard special page When boxes are run near (or to) OOM, we have a problem with the discard page allocation in sd. If we fail allocating the special page, we return busy, and it'll get retried. But since ordering is honored for dispatch requests, we can keep retrying this same IO and failing. Behind that IO could be requests that want to free memory, but they never get the chance. This means you get repeated spews of traces like this: [1201401.625972] Call Trace: [1201401.631748] dump_stack+0x4d/0x65 [1201401.639445] warn_alloc+0xec/0x190 [1201401.647335] __alloc_pages_slowpath+0xe84/0xf30 [1201401.657722] ? get_page_from_freelist+0x11b/0xb10 [1201401.668475] ? __alloc_pages_slowpath+0x2e/0xf30 [1201401.679054] __alloc_pages_nodemask+0x1f9/0x210 [1201401.689424] alloc_pages_current+0x8c/0x110 [1201401.699025] sd_setup_write_same16_cmnd+0x51/0x150 [1201401.709987] sd_init_command+0x49c/0xb70 [1201401.719029] scsi_setup_cmnd+0x9c/0x160 [1201401.727877] scsi_queue_rq+0x4d9/0x610 [1201401.736535] blk_mq_dispatch_rq_list+0x19a/0x360 [1201401.747113] blk_mq_sched_dispatch_requests+0xff/0x190 [1201401.758844] __blk_mq_run_hw_queue+0x95/0xa0 [1201401.768653] blk_mq_run_work_fn+0x2c/0x30 [1201401.777886] process_one_work+0x14b/0x400 [1201401.787119] worker_thread+0x4b/0x470 [1201401.795586] kthread+0x110/0x150 [1201401.803089] ? rescuer_thread+0x320/0x320 [1201401.812322] ? kthread_park+0x90/0x90 [1201401.820787] ? do_syscall_64+0x53/0x150 [1201401.829635] ret_from_fork+0x29/0x40 Ensure that the discard page allocation has a mempool backing, so we know we can make progress. Cc: stable@vger.kernel.org Signed-off-by: Jens Axboe <axboe@kernel.dk> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>