Christian Hesse <list@xxxxxxxx> writes:
> Hello everybody,
>
> with linux 4.1.x I am hit by this issue with RAID5:
>
> BUG: unable to handle kernel NULL pointer dereference at (null)
> IP: [<ffffffffa05a4b91>] get_free_stripe+0x31/0xf0 [raid456]
Thank for the report.
Please add upstrem commit:
Commit: 49895bcc7e56 ("md/raid5: don't let shrink_slab shrink too far.")
fix it.
NeilBrown
> PGD bbb4e067 PUD a371f067 PMD 0
> Oops: 0000 [#1] PREEMPT SMP
> Modules linked in: fuse raid456 nft_reject_inet nf_reject_ipv4 async_raid6_recov nf_reject_ipv6 async_memcpy nft_reject async_pq async_xor xor async_tx vmw_vsock_vmci_transport vsock nft_meta iosf_mbi nf_conntrack_ipv6 coretemp nf_defrag_ipv6 crct10dif_pclmul crc32_pclmul ghash_clmulni_intel raid6_pq mousedev aesni_intel nf_conntrack_ipv4 ppdev nf_defrag_ipv4 aes_x86_64 md_mod nft_ct nf_conntrack lrw gf128mul glue_helper vmw_balloon ablk_helper cryptd psmouse nft_hash serio_raw pcspkr nft_rbtree nf_tables_inet nf_tables_ipv6 vmwgfx nf_tables_ipv4 nf_tables ttm drm_kms_helper battery drm nfnetlink i2c_piix4 irda acpi_cpufreq vmw_vmci i2c_core shpchp evdev parport_pc crc_ccitt parport processor mac_hid ac sch_fq_codel nfs lockd grace sunrpc fscache ip_tables x_tables ext4 crc16 mbcache
> jbd2 dm_snapshot dm_bufio squashfs loop dm_mirror dm_region_hash dm_log dm_mod sd_mod sr_mod cdrom ata_generic pata_acpi mptsas ata_piix scsi_transport_sas mptscsih libata mptbase crc32c_intel vmxnet3 scsi_mod atkbd libps2 intel_agp intel_gtt floppy i8042 serio button
> CPU: 0 PID: 430 Comm: rsync Tainted: G W 4.1.6-2-ARCH #1
> Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 07/09/2012
> task: ffff8800bb5628c0 ti: ffff880021ad8000 task.ti: ffff880021ad8000
> RIP: 0010:[<ffffffffa05a4b91>] [<ffffffffa05a4b91>] get_free_stripe+0x31/0xf0 [raid456]
> RSP: 0018:ffff880021adb748 EFLAGS: 00010086
> RAX: fffffffffffffff0 RBX: 0000000000000000 RCX: 00000000000000ff
> RDX: 0000000100100001 RSI: 00000000ffffffff RDI: ffff8800bb756800
> RBP: ffff880021adb778 R08: ffff880235eee380 R09: ffff880235eede00
> R10: ffffea00000de600 R11: 0000000000019d48 R12: ffff8800bb756800
> R13: ffff8800bb756806 R14: ffff8800bb756990 R15: 0000000000000080
> FS: 00007f5bc71d6700(0000) GS:ffff88023fc00000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 0000000000000000 CR3: 00000000bb40f000 CR4: 00000000000406f0
> Stack:
> ffff880021adb778 00000000ffffffff ffff8800bb756800 ffff8800bb756806
> ffff8800bb756938 0000000000000080 ffff880021adb7a8 ffffffffa05a9814
> ffff880021adb7a8 000000000000000b ffff8800bb756800 ffff880021adb870
> Call Trace:
> [<ffffffffa05a9814>] drop_one_stripe+0x44/0xb0 [raid456]
> [<ffffffffa05a9a6a>] raid5_cache_scan+0x6a/0x90 [raid456]
> [<ffffffff81179299>] shrink_slab+0x229/0x440
> [<ffffffff8117cbca>] shrink_zone+0x2ca/0x2e0
> [<ffffffff8117cd53>] do_try_to_free_pages+0x173/0x410
> [<ffffffff8117d097>] try_to_free_pages+0xa7/0x1a0
> [<ffffffff8116fcbf>] __alloc_pages_nodemask+0x5ff/0x9e0
> [<ffffffff811b71f1>] alloc_pages_current+0x91/0x110
> [<ffffffff81166657>] __page_cache_alloc+0xa7/0xd0
> [<ffffffff811738e0>] __do_page_cache_readahead+0x120/0x290
> [<ffffffff81173b30>] ondemand_readahead+0xe0/0x2a0
> [<ffffffff811666ac>] ? pagecache_get_page+0x2c/0x1f0
> [<ffffffff81173e3e>] page_cache_sync_readahead+0x2e/0x50
> [<ffffffff81167b44>] generic_file_read_iter+0x4e4/0x600
> [<ffffffff811e062e>] __vfs_read+0xce/0x100
> [<ffffffff811e0f07>] vfs_read+0x87/0x140
> [<ffffffff811e1d19>] SyS_read+0x59/0xd0
> [<ffffffff8158bfee>] system_call_fastpath+0x12/0x71
> Code: 48 63 c6 48 c1 e0 04 48 89 e5 41 57 41 56 4c 8d b4 07 a0 01 00 00 41 55 41 54 53 48 83 ec 08 49 8b 1e 49 39 de 0f 84 b7 00 00 00 <48> 8b 13 48 8b 43 08 41 89 f5 49 89 fc 4c 8d 7b f0 48 89 42 08
> RIP [<ffffffffa05a4b91>] get_free_stripe+0x31/0xf0 [raid456]
> RSP <ffff880021adb748>
> CR2: 0000000000000000
> ---[ end trace c34528a6b22f7fec ]---
>
> I applied a patch series by Yuanhan Liu for preparation [0][1][2] and a patch
> by Neil Brown to avoid a race condition [3]. This still happens.
>
> [0]
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/patch/?id=9f3520c3
> [1]
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/patch/?id=b1b46486
> [2]
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/patch/?id=e9e4c377
> [3]
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/patch/?id=2d5b569b
>
> --
> Best regards,
> Chris
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