4.14-stable review patch. If anyone has any objections, please let me know.
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From: Jens Axboe axboe@kernel.dk
commit 61cce6f6eeced5ddd9cac55e807fe28b4f18c1ba upstream.
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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/scsi/sd.c | 23 +++++++++++++++++++---- 1 file changed, 19 insertions(+), 4 deletions(-)
--- a/drivers/scsi/sd.c +++ b/drivers/scsi/sd.c @@ -133,6 +133,7 @@ static DEFINE_MUTEX(sd_ref_mutex);
static struct kmem_cache *sd_cdb_cache; static mempool_t *sd_cdb_pool; +static mempool_t *sd_page_pool;
static const char *sd_cache_types[] = { "write through", "none", "write back", @@ -759,9 +760,10 @@ static int sd_setup_unmap_cmnd(struct sc unsigned int data_len = 24; char *buf;
- rq->special_vec.bv_page = alloc_page(GFP_ATOMIC | __GFP_ZERO); + rq->special_vec.bv_page = mempool_alloc(sd_page_pool, GFP_ATOMIC); if (!rq->special_vec.bv_page) return BLKPREP_DEFER; + clear_highpage(rq->special_vec.bv_page); rq->special_vec.bv_offset = 0; rq->special_vec.bv_len = data_len; rq->rq_flags |= RQF_SPECIAL_PAYLOAD; @@ -792,9 +794,10 @@ static int sd_setup_write_same16_cmnd(st u32 nr_sectors = blk_rq_sectors(rq) >> (ilog2(sdp->sector_size) - 9); u32 data_len = sdp->sector_size;
- rq->special_vec.bv_page = alloc_page(GFP_ATOMIC | __GFP_ZERO); + rq->special_vec.bv_page = mempool_alloc(sd_page_pool, GFP_ATOMIC); if (!rq->special_vec.bv_page) return BLKPREP_DEFER; + clear_highpage(rq->special_vec.bv_page); rq->special_vec.bv_offset = 0; rq->special_vec.bv_len = data_len; rq->rq_flags |= RQF_SPECIAL_PAYLOAD; @@ -822,9 +825,10 @@ static int sd_setup_write_same10_cmnd(st u32 nr_sectors = blk_rq_sectors(rq) >> (ilog2(sdp->sector_size) - 9); u32 data_len = sdp->sector_size;
- rq->special_vec.bv_page = alloc_page(GFP_ATOMIC | __GFP_ZERO); + rq->special_vec.bv_page = mempool_alloc(sd_page_pool, GFP_ATOMIC); if (!rq->special_vec.bv_page) return BLKPREP_DEFER; + clear_highpage(rq->special_vec.bv_page); rq->special_vec.bv_offset = 0; rq->special_vec.bv_len = data_len; rq->rq_flags |= RQF_SPECIAL_PAYLOAD; @@ -1299,7 +1303,7 @@ static void sd_uninit_command(struct scs sd_zbc_write_unlock_zone(SCpnt);
if (rq->rq_flags & RQF_SPECIAL_PAYLOAD) - __free_page(rq->special_vec.bv_page); + mempool_free(rq->special_vec.bv_page, sd_page_pool);
if (SCpnt->cmnd != scsi_req(rq)->cmd) { cmnd = SCpnt->cmnd; @@ -3655,6 +3659,13 @@ static int __init init_sd(void) goto err_out_cache; }
+ sd_page_pool = mempool_create_page_pool(SD_MEMPOOL_SIZE, 0); + if (!sd_page_pool) { + printk(KERN_ERR "sd: can't init discard page pool\n"); + err = -ENOMEM; + goto err_out_ppool; + } + err = scsi_register_driver(&sd_template.gendrv); if (err) goto err_out_driver; @@ -3662,6 +3673,9 @@ static int __init init_sd(void) return 0;
err_out_driver: + mempool_destroy(sd_page_pool); + +err_out_ppool: mempool_destroy(sd_cdb_pool);
err_out_cache: @@ -3688,6 +3702,7 @@ static void __exit exit_sd(void)
scsi_unregister_driver(&sd_template.gendrv); mempool_destroy(sd_cdb_pool); + mempool_destroy(sd_page_pool); kmem_cache_destroy(sd_cdb_cache);
class_unregister(&sd_disk_class);