I just got qemu-system-s39: page allocation failure: order:0, mode:0x2200000(GFP_NOWAIT|__GFP_NOTRACK) CPU: 0 PID: 6664 Comm: qemu-system-s39 Tainted: G 4.9.0-rc2+ #44 [...] ([<000000000011230a>] show_trace+0x62/0x78) ([<00000000001123da>] show_stack+0x72/0xf0) ([<00000000004a7906>] dump_stack+0x7e/0xb0) ([<000000000025df14>] warn_alloc+0x11c/0x148) ([<000000000025e48c>] __alloc_pages_nodemask+0x4c4/0xe50) ([<00000000002be590>] new_slab+0x560/0x778 ([<00000000002c0adc>] ___slab_alloc.constprop.29+0x2b4/0x368) ([<00000000002c0bc4>] __slab_alloc.constprop.28+0x34/0x50) ([<00000000002c10aa>] kmem_cache_alloc_trace+0x20a/0x270) ([<0000000000257934>] mempool_create_node+0x5c/0x188) ([<00000000004745d6>] blk_init_rl+0xa6/0xe0) ([<0000000000493f58>] blkg_alloc+0x150/0x2a8) ([<0000000000494404>] blkg_create+0x354/0x3b0) ([<00000000004962c0>] blkg_lookup_create+0x100/0x180) ([<0000000000472cd4>] generic_make_request_checks+0x504/0x590) ([<0000000000474a66>] generic_make_request+0x2e/0x1b0) ([<0000000000474c8c>] submit_bio+0xa4/0x178) ([<000003ff80c64670>] btrfs_map_bio+0x1c0/0x3c8 [btrfs]) ([<000003ff80c3075c>] btrfs_submit_bio_hook+0x104/0x210 [...]
Seems that blk-cgroup can handle allocation failures quite will - it does check the result and the system continues to run, so let's make allocation failures silent in here. There are other GFP_NOWAIT places in that file, but not all seem to check the return value. In addition this warning seems to be the only one that I can reliably reproduce so I decided to only touch blkg_create. Signed-off-by: Christian Borntraeger <[email protected]> --- block/blk-cgroup.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c index b08ccbb..d22bd95 100644 --- a/block/blk-cgroup.c +++ b/block/blk-cgroup.c @@ -185,7 +185,8 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, } wb_congested = wb_congested_get_create(&q->backing_dev_info, - blkcg->css.id, GFP_NOWAIT); + blkcg->css.id, + GFP_NOWAIT | __GFP_NOWARN); if (!wb_congested) { ret = -ENOMEM; goto err_put_css; @@ -193,7 +194,7 @@ static struct blkcg_gq *blkg_create(struct blkcg *blkcg, /* allocate */ if (!new_blkg) { - new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT); + new_blkg = blkg_alloc(blkcg, q, GFP_NOWAIT | __GFP_NOWARN); if (unlikely(!new_blkg)) { ret = -ENOMEM; goto err_put_congested; -- 2.5.5
