On Mon, Sep 18, 2017 at 02:49:19PM -0400, Johannes Weiner wrote: > For quick per-memcg indexing, slab caches and list_lru structures > maintain linear arrays of descriptors. As the number of concurrent > memory cgroups in the system goes up, this requires large contiguous > allocations (8k cgroups = order-5, 16k cgroups = order-6 etc.) for > every existing slab cache and list_lru, which can easily fail on > loaded systems. E.g.: > > mkdir: page allocation failure: order:5, mode:0x14040c0(GFP_KERNEL|__GFP_COMP), nodemask=(null) > CPU: 1 PID: 6399 Comm: mkdir Not tainted 4.13.0-mm1-00065-g720bbe532b7c-dirty #481 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-20170228_101828-anatol 04/01/2014 > Call Trace: > dump_stack+0x70/0x9d > warn_alloc+0xd6/0x170 > ? __alloc_pages_direct_compact+0x4c/0x110 > __alloc_pages_nodemask+0xf50/0x1430 > ? __lock_acquire+0xd19/0x1360 > ? memcg_update_all_list_lrus+0x2e/0x2e0 > ? __mutex_lock+0x7c/0x950 > ? memcg_update_all_list_lrus+0x2e/0x2e0 > alloc_pages_current+0x60/0xc0 > kmalloc_order_trace+0x29/0x1b0 > __kmalloc+0x1f4/0x320 > memcg_update_all_list_lrus+0xca/0x2e0 > mem_cgroup_css_alloc+0x612/0x670 > cgroup_apply_control_enable+0x19e/0x360 > cgroup_mkdir+0x322/0x490 > kernfs_iop_mkdir+0x55/0x80 > vfs_mkdir+0xd0/0x120 > SyS_mkdirat+0x6c/0xe0 > SyS_mkdir+0x14/0x20 > entry_SYSCALL_64_fastpath+0x18/0xad > RIP: 0033:0x7f9ff36cee87 > RSP: 002b:00007ffc7612d758 EFLAGS: 00000202 ORIG_RAX: 0000000000000053 > RAX: ffffffffffffffda RBX: 00007ffc7612da48 RCX: 00007f9ff36cee87 > RDX: 00000000000001ff RSI: 00000000000001ff RDI: 00007ffc7612de86 > RBP: 0000000000000002 R08: 00000000000001ff R09: 0000000000401db0 > R10: 00000000000001e2 R11: 0000000000000202 R12: 0000000000000000 > R13: 00007ffc7612da40 R14: 0000000000000000 R15: 0000000000000000 > Mem-Info: > active_anon:2965 inactive_anon:19 isolated_anon:0 > active_file:100270 inactive_file:98846 isolated_file:0 > unevictable:0 dirty:0 writeback:0 unstable:0 > slab_reclaimable:7328 slab_unreclaimable:16402 > mapped:771 shmem:52 pagetables:278 bounce:0 > free:13718 free_pcp:0 free_cma:0 > > This output is from an artificial reproducer, but we have repeatedly > observed order-7 failures in production in the Facebook fleet. These > systems become useless as they cannot run more jobs, even though there > is plenty of memory to allocate 128 individual pages. > > Use kvmalloc and kvzalloc to fall back to vmalloc space if these > arrays prove too large for allocating them physically contiguous. > > Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx> Thanks to kvmalloc/kvfree helpers this looks really neat. Should've been done like that long ago. Acked-by: Vladimir Davydov <vdavydov.dev@xxxxxxxxx> Thanks, Vladimir -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
