diff options
author | Weston Andros Adamson <dros@monkey.org> | 2016-05-25 17:07:23 +0300 |
---|---|---|
committer | Anna Schumaker <Anna.Schumaker@Netapp.com> | 2016-05-25 19:59:01 +0300 |
commit | ade8febde0271513360bac44883dbebad44276c3 (patch) | |
tree | 6458884e81f473a534467c66313036627962dfc2 /fs | |
parent | 2997bfd0492d33d230b1475909a0211157a734bc (diff) | |
download | linux-ade8febde0271513360bac44883dbebad44276c3.tar.xz |
nfs: avoid race that crashes nfs_init_commit
Since the patch "NFS: Allow multiple commit requests in flight per file"
we can run multiple simultaneous commits on the same inode. This
introduced a race over collecting pages to commit that made it possible
to call nfs_init_commit() with an empty list - which causes crashes like
the one below.
The fix is to catch this race and avoid calling nfs_init_commit and
initiate_commit when there is no work to do.
Here is the crash:
[600522.076832] BUG: unable to handle kernel NULL pointer dereference at 0000000000000040
[600522.078475] IP: [<ffffffffa0479e72>] nfs_init_commit+0x22/0x130 [nfs]
[600522.078745] PGD 4272b1067 PUD 4272cb067 PMD 0
[600522.078972] Oops: 0000 [#1] SMP
[600522.079204] Modules linked in: nfsv3 nfs_layout_flexfiles rpcsec_gss_krb5 nfsv4 dns_resolver nfs fscache dcdbas ip6t_rpfilter ip6t_REJECT nf_reject_ipv6 xt_conntrack ebtable_nat ebtable_broute bridge stp llc ebtable_filter ebtables ip6table_nat nf_conntrack_ipv6 nf_defrag_ipv6 nf_nat_ipv6 ip6table_mangle ip6table_security ip6table_raw ip6table_filter ip6_tables iptable_nat nf_conntrack_ipv4 nf_defrag_ipv4 nf_nat_ipv4 nf_nat nf_conntrack iptable_mangle iptable_security iptable_raw vmw_vsock_vmci_transport vsock bonding ipmi_devintf ipmi_msghandler coretemp crct10dif_pclmul crc32_pclmul ghash_clmulni_intel ppdev vmw_balloon parport_pc parport acpi_cpufreq vmw_vmci i2c_piix4 shpchp nfsd auth_rpcgss nfs_acl lockd grace sunrpc xfs libcrc32c vmwgfx drm_kms_helper ttm drm crc32c_intel serio_raw vmxnet3
[600522.081380] vmw_pvscsi ata_generic pata_acpi
[600522.081809] CPU: 3 PID: 15667 Comm: /usr/bin/python Not tainted 4.1.9-100.pd.88.el7.x86_64 #1
[600522.082281] Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform, BIOS 6.00 09/30/2014
[600522.082814] task: ffff8800bbbfa780 ti: ffff88042ae84000 task.ti: ffff88042ae84000
[600522.083378] RIP: 0010:[<ffffffffa0479e72>] [<ffffffffa0479e72>] nfs_init_commit+0x22/0x130 [nfs]
[600522.083973] RSP: 0018:ffff88042ae87438 EFLAGS: 00010246
[600522.084571] RAX: 0000000000000000 RBX: ffff880003485e40 RCX: ffff88042ae87588
[600522.085188] RDX: 0000000000000000 RSI: ffff88042ae874b0 RDI: ffff880003485e40
[600522.085756] RBP: ffff88042ae87448 R08: ffff880003486010 R09: ffff88042ae874b0
[600522.086332] R10: 0000000000000000 R11: 0000000000000005 R12: ffff88042ae872d0
[600522.086905] R13: ffff88042ae874b0 R14: ffff880003485e40 R15: ffff88042704c840
[600522.087484] FS: 00007f4728ff2740(0000) GS:ffff88043fd80000(0000) knlGS:0000000000000000
[600522.088070] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b
[600522.088663] CR2: 0000000000000040 CR3: 000000042b6aa000 CR4: 00000000001406e0
[600522.089327] Stack:
[600522.089926] 0000000000000001 ffff88042ae87588 ffff88042ae874f8 ffffffffa04f09fa
[600522.090549] 0000000000017840 0000000000017840 ffff88042ae87588 ffff8803258d9930
[600522.091169] ffff88042ae87578 ffffffffa0563d80 0000000000000000 ffff88042704c840
[600522.091789] Call Trace:
[600522.092420] [<ffffffffa04f09fa>] pnfs_generic_commit_pagelist+0x1da/0x320 [nfsv4]
[600522.093052] [<ffffffffa0563d80>] ? ff_layout_commit_prepare_v3+0x30/0x30 [nfs_layout_flexfiles]
[600522.093696] [<ffffffffa0562645>] ff_layout_commit_pagelist+0x15/0x20 [nfs_layout_flexfiles]
[600522.094359] [<ffffffffa047bc78>] nfs_generic_commit_list+0xe8/0x120 [nfs]
[600522.095032] [<ffffffffa047bd6a>] nfs_commit_inode+0xba/0x110 [nfs]
[600522.095719] [<ffffffffa046ac54>] nfs_release_page+0x44/0xd0 [nfs]
[600522.096410] [<ffffffff811a8122>] try_to_release_page+0x32/0x50
[600522.097109] [<ffffffff811bd4f1>] shrink_page_list+0x961/0xb30
[600522.097812] [<ffffffff811bdced>] shrink_inactive_list+0x1cd/0x550
[600522.098530] [<ffffffff811bea65>] shrink_lruvec+0x635/0x840
[600522.099250] [<ffffffff811bed60>] shrink_zone+0xf0/0x2f0
[600522.099974] [<ffffffff811bf312>] do_try_to_free_pages+0x192/0x470
[600522.100709] [<ffffffff811bf6ca>] try_to_free_pages+0xda/0x170
[600522.101464] [<ffffffff811b2198>] __alloc_pages_nodemask+0x588/0x970
[600522.102235] [<ffffffff811fbbd5>] alloc_pages_vma+0xb5/0x230
[600522.103000] [<ffffffff813a1589>] ? cpumask_any_but+0x39/0x50
[600522.103774] [<ffffffff811d6115>] wp_page_copy.isra.55+0x95/0x490
[600522.104558] [<ffffffff810e3438>] ? __wake_up+0x48/0x60
[600522.105357] [<ffffffff811d7d3b>] do_wp_page+0xab/0x4f0
[600522.106137] [<ffffffff810a1bbb>] ? release_task+0x36b/0x470
[600522.106902] [<ffffffff8126dbd7>] ? eventfd_ctx_read+0x67/0x1c0
[600522.107659] [<ffffffff811da2a8>] handle_mm_fault+0xc78/0x1900
[600522.108431] [<ffffffff81067ef1>] __do_page_fault+0x181/0x420
[600522.109173] [<ffffffff811446a6>] ? __audit_syscall_exit+0x1e6/0x280
[600522.109893] [<ffffffff810681c0>] do_page_fault+0x30/0x80
[600522.110594] [<ffffffff81024f36>] ? syscall_trace_leave+0xc6/0x120
[600522.111288] [<ffffffff81790a58>] page_fault+0x28/0x30
[600522.111947] Code: 5d c3 0f 1f 80 00 00 00 00 0f 1f 44 00 00 55 4c 8d 87 d0 01 00 00 48 89 e5 53 48 89 fb 48 83 ec 08 4c 8b 0e 49 8b 41 18 4c 39 ce <48> 8b 40 40 4c 8b 50 30 74 24 48 8b 87 d0 01 00 00 48 8b 7e 08
[600522.113343] RIP [<ffffffffa0479e72>] nfs_init_commit+0x22/0x130 [nfs]
[600522.114003] RSP <ffff88042ae87438>
[600522.114636] CR2: 0000000000000040
Fixes: af7cf057 (NFS: Allow multiple commit requests in flight per file)
CC: stable@vger.kernel.org
Signed-off-by: Weston Andros Adamson <dros@primarydata.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Diffstat (limited to 'fs')
-rw-r--r-- | fs/nfs/pnfs_nfs.c | 28 | ||||
-rw-r--r-- | fs/nfs/write.c | 4 |
2 files changed, 32 insertions, 0 deletions
diff --git a/fs/nfs/pnfs_nfs.c b/fs/nfs/pnfs_nfs.c index d2a7c9f7aa94..0dfc476da3e1 100644 --- a/fs/nfs/pnfs_nfs.c +++ b/fs/nfs/pnfs_nfs.c @@ -246,6 +246,23 @@ void pnfs_fetch_commit_bucket_list(struct list_head *pages, } +/* Helper function for pnfs_generic_commit_pagelist to catch an empty + * page list. This can happen when two commits race. */ +static bool +pnfs_generic_commit_cancel_empty_pagelist(struct list_head *pages, + struct nfs_commit_data *data, + struct nfs_commit_info *cinfo) +{ + if (list_empty(pages)) { + if (atomic_dec_and_test(&cinfo->mds->rpcs_out)) + wake_up_atomic_t(&cinfo->mds->rpcs_out); + nfs_commitdata_release(data); + return true; + } + + return false; +} + /* This follows nfs_commit_list pretty closely */ int pnfs_generic_commit_pagelist(struct inode *inode, struct list_head *mds_pages, @@ -280,6 +297,11 @@ pnfs_generic_commit_pagelist(struct inode *inode, struct list_head *mds_pages, list_for_each_entry_safe(data, tmp, &list, pages) { list_del_init(&data->pages); if (data->ds_commit_index < 0) { + /* another commit raced with us */ + if (pnfs_generic_commit_cancel_empty_pagelist(mds_pages, + data, cinfo)) + continue; + nfs_init_commit(data, mds_pages, NULL, cinfo); nfs_initiate_commit(NFS_CLIENT(inode), data, NFS_PROTO(data->inode), @@ -288,6 +310,12 @@ pnfs_generic_commit_pagelist(struct inode *inode, struct list_head *mds_pages, LIST_HEAD(pages); pnfs_fetch_commit_bucket_list(&pages, data, cinfo); + + /* another commit raced with us */ + if (pnfs_generic_commit_cancel_empty_pagelist(&pages, + data, cinfo)) + continue; + nfs_init_commit(data, &pages, data->lseg, cinfo); initiate_commit(data, how); } diff --git a/fs/nfs/write.c b/fs/nfs/write.c index 54a4eb6bc462..e1c74d3db64d 100644 --- a/fs/nfs/write.c +++ b/fs/nfs/write.c @@ -1710,6 +1710,10 @@ nfs_commit_list(struct inode *inode, struct list_head *head, int how, { struct nfs_commit_data *data; + /* another commit raced with us */ + if (list_empty(head)) + return 0; + data = nfs_commitdata_alloc(); if (!data) |