From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH V4] mlx4_core: allocate ICM memory in page size chunks Date: Tue, 29 May 2018 23:34:34 -0400 Message-ID: <7a353b65-6b7f-1aee-1c48-e83c8e02f693@gmail.com> References: <20180523232246.20445-1-qing.huang@oracle.com> <20180525.102321.858995452200286788.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Cc: tariqt@mellanox.com, haakon.bugge@oracle.com, yanjun.zhu@oracle.com, netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org, gi-oh.kim@profitbricks.com To: David Miller , qing.huang@oracle.com Return-path: In-Reply-To: <20180525.102321.858995452200286788.davem@davemloft.net> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 05/25/2018 10:23 AM, David Miller wrote: > From: Qing Huang > Date: Wed, 23 May 2018 16:22:46 -0700 > >> When a system is under memory presure (high usage with fragments), >> the original 256KB ICM chunk allocations will likely trigger kernel >> memory management to enter slow path doing memory compact/migration >> ops in order to complete high order memory allocations. >> >> When that happens, user processes calling uverb APIs may get stuck >> for more than 120s easily even though there are a lot of free pages >> in smaller chunks available in the system. >> >> Syslog: >> ... >> Dec 10 09:04:51 slcc03db02 kernel: [397078.572732] INFO: task >> oracle_205573_e:205573 blocked for more than 120 seconds. >> ... >> >> With 4KB ICM chunk size on x86_64 arch, the above issue is fixed. >> >> However in order to support smaller ICM chunk size, we need to fix >> another issue in large size kcalloc allocations. >> >> E.g. >> Setting log_num_mtt=30 requires 1G mtt entries. With the 4KB ICM chunk >> size, each ICM chunk can only hold 512 mtt entries (8 bytes for each mtt >> entry). So we need a 16MB allocation for a table->icm pointer array to >> hold 2M pointers which can easily cause kcalloc to fail. >> >> The solution is to use kvzalloc to replace kcalloc which will fall back >> to vmalloc automatically if kmalloc fails. >> >> Signed-off-by: Qing Huang >> Acked-by: Daniel Jurgens >> Reviewed-by: Zhu Yanjun > > Applied, thanks. > I must say this patch causes regressions here. KASAN is not happy. It looks that you guys did not really looked at mlx4_alloc_icm() This function is properly handling high order allocations with fallbacks to order-0 pages under high memory pressure. BUG: KASAN: slab-out-of-bounds in to_rdma_ah_attr+0x808/0x9e0 [mlx4_ib] Read of size 4 at addr ffff8817df584f68 by task qp_listing_test/92585 CPU: 38 PID: 92585 Comm: qp_listing_test Tainted: G O Call Trace: [] dump_stack+0x4d/0x72 [] print_address_description+0x6f/0x260 [] kasan_report+0x257/0x370 [] __asan_report_load4_noabort+0x19/0x20 [] to_rdma_ah_attr+0x808/0x9e0 [mlx4_ib] [] mlx4_ib_query_qp+0x1213/0x1660 [mlx4_ib] [] qpstat_print_qp+0x13b/0x500 [ib_uverbs] [] qpstat_seq_show+0x4a/0xb0 [ib_uverbs] [] seq_read+0xa9c/0x1230 [] proc_reg_read+0xc1/0x180 [] __vfs_read+0xe8/0x730 [] vfs_read+0xf7/0x300 [] SyS_read+0xd2/0x1b0 [] do_syscall_64+0x186/0x420 [] entry_SYSCALL_64_after_hwframe+0x3d/0xa2 RIP: 0033:0x7f851a7bb30d RSP: 002b:00007ffd09a758c0 EFLAGS: 00000293 ORIG_RAX: 0000000000000000 RAX: ffffffffffffffda RBX: 00007f84ff959440 RCX: 00007f851a7bb30d RDX: 000000000003fc00 RSI: 00007f84ff60a000 RDI: 000000000000000b RBP: 00007ffd09a75900 R08: 00000000ffffffff R09: 0000000000000000 R10: 0000000000000022 R11: 0000000000000293 R12: 0000000000000000 R13: 000000000003ffff R14: 000000000003ffff R15: 00007f84ff60a000 Allocated by task 4488: save_stack+0x46/0xd0 kasan_kmalloc+0xad/0xe0 __kmalloc+0x101/0x5e0 ib_register_device+0xc03/0x1250 [ib_core] mlx4_ib_add+0x27d6/0x4dd0 [mlx4_ib] mlx4_add_device+0xa9/0x340 [mlx4_core] mlx4_register_interface+0x16e/0x390 [mlx4_core] xhci_pci_remove+0x7a/0x180 [xhci_pci] do_one_initcall+0xa0/0x230 do_init_module+0x1b9/0x5a4 load_module+0x63e6/0x94c0 SYSC_init_module+0x1a4/0x1c0 SyS_init_module+0xe/0x10 do_syscall_64+0x186/0x420 entry_SYSCALL_64_after_hwframe+0x3d/0xa2 Freed by task 0: (stack is not available) The buggy address belongs to the object at ffff8817df584f40 which belongs to the cache kmalloc-32 of size 32 The buggy address is located 8 bytes to the right of 32-byte region [ffff8817df584f40, ffff8817df584f60) The buggy address belongs to the page: page:ffffea005f7d6100 count:1 mapcount:0 mapping:ffff8817df584000 index:0xffff8817df584fc1 flags: 0x880000000000100(slab) raw: 0880000000000100 ffff8817df584000 ffff8817df584fc1 000000010000003f raw: ffffea005f3ac0a0 ffffea005c476760 ffff8817fec00900 ffff883ff78d26c0 page dumped because: kasan: bad access detected page->mem_cgroup:ffff883ff78d26c0 Memory state around the buggy address: ffff8817df584e00: 00 03 fc fc fc fc fc fc 00 03 fc fc fc fc fc fc ffff8817df584e80: 00 00 00 04 fc fc fc fc 00 00 00 fc fc fc fc fc >ffff8817df584f00: fb fb fb fb fc fc fc fc 00 00 00 00 fc fc fc fc ^ ffff8817df584f80: fb fb fb fb fc fc fc fc fc fc fc fc fc fc fc fc ffff8817df585000: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb I will test : diff --git a/drivers/net/ethernet/mellanox/mlx4/icm.c b/drivers/net/ethernet/mellanox/mlx4/icm.c index 685337d58276fc91baeeb64387c52985e1bc6dda..4d2a71381acb739585d662175e86caef72338097 100644 --- a/drivers/net/ethernet/mellanox/mlx4/icm.c +++ b/drivers/net/ethernet/mellanox/mlx4/icm.c @@ -43,12 +43,13 @@ #include "fw.h" /* - * We allocate in page size (default 4KB on many archs) chunks to avoid high - * order memory allocations in fragmented/high usage memory situation. + * We allocate in as big chunks as we can, up to a maximum of 256 KB + * per chunk. Note that the chunks are not necessarily in contiguous + * physical memory. */ enum { - MLX4_ICM_ALLOC_SIZE = PAGE_SIZE, - MLX4_TABLE_CHUNK_SIZE = PAGE_SIZE, + MLX4_ICM_ALLOC_SIZE = 1 << 18, + MLX4_TABLE_CHUNK_SIZE = 1 << 18 }; static void mlx4_free_icm_pages(struct mlx4_dev *dev, struct mlx4_icm_chunk *chunk)