On Apr 22, 2014, at 4:02 PM, Weston Andros Adamson <dros@xxxxxxxxxxxxxxx> wrote:
> Hold the lock while modifying commit info dataserver buckets.
>
> The following oops can be reproduced by running iozone for a while against
> a 2 DS pynfs filelayout server.
>
> general protection fault: 0000 [#1] SMP DEBUG_PAGEALLOC
> Modules linked in: nfs_layout_nfsv41_files rpcsec_gss_krb5 nfsv4 nfs fscache
> CPU: 0 PID: 903 Comm: iozone Not tainted 3.15.0-rc1-branch-dros_testing+ #44
> Hardware name: VMware, Inc. VMware Virtual Platform/440BX Desktop Reference
> task: ffff880078164480 ti: ffff88006e972000 task.ti: ffff88006e972000
> RIP: 0010:[<ffffffffa01936e1>] [<ffffffffa01936e1>] nfs_init_commit+0x22/0x
> RSP: 0018:ffff88006e973d30 EFLAGS: 00010246
> RAX: ffff88006e973e00 RBX: ffff88006e828800 RCX: ffff88006e973e10
> RDX: 0000000000000000 RSI: ffff88006e973e00 RDI: dead4ead00000000
> RBP: ffff88006e973d38 R08: ffff88006e8289d8 R09: 0000000000000000
> R10: ffff88006e8289d8 R11: 0000000000016988 R12: ffff88006e973b98
> R13: ffff88007a0a6648 R14: ffff88006e973e10 R15: ffff88006e828800
> FS: 00007f2ce396b740(0000) GS:ffff88007f200000(0000) knlGS:0000000000000000
> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007f03278a1000 CR3: 0000000079043000 CR4: 00000000001407f0
> Stack:
> ffff88006e8289d8 ffff88006e973da8 ffffffffa00f144f ffff88006e9478c0
> ffff88006e973e00 ffff88006de21080 0000000100000002 ffff880079be6c48
> ffff88006e973d70 ffff88006e973d70 ffff88006e973e10 ffff88006de21080
> Call Trace:
> [<ffffffffa00f144f>] filelayout_commit_pagelist+0x1ae/0x34a [nfs_layout_nfsv
> [<ffffffffa0194f72>] nfs_generic_commit_list+0x92/0xc4 [nfs]
> [<ffffffffa0195053>] nfs_commit_inode+0xaf/0x114 [nfs]
> [<ffffffffa01892bd>] nfs_file_fsync_commit+0x82/0xbe [nfs]
> [<ffffffffa01ceb0d>] nfs4_file_fsync+0x59/0x9b [nfsv4]
> [<ffffffff8114ee3c>] vfs_fsync_range+0x18/0x20
> [<ffffffff8114ee60>] vfs_fsync+0x1c/0x1e
> [<ffffffffa01891c2>] nfs_file_flush+0x7f/0x84 [nfs]
> [<ffffffff81127a43>] filp_close+0x3c/0x72
> [<ffffffff81140e12>] __close_fd+0x82/0x9a
> [<ffffffff81127a9c>] SyS_close+0x23/0x4c
> [<ffffffff814acd12>] system_call_fastpath+0x16/0x1b
> Code: 5b 41 5c 41 5d 41 5e 5d c3 0f 1f 44 00 00 55 48 89 e5 53 48 89 fb 48 8
> RIP [<ffffffffa01936e1>] nfs_init_commit+0x22/0xe1 [nfs]
> RSP <ffff88006e973d30>
> ---[ end trace 732fe6419b235e2f ]---
>
> Suggested-by: Trond Myklebust <trond.myklebust@xxxxxxxxxxxxxxx>
> Signed-off-by: Weston Andros Adamson <dros@xxxxxxxxxxxxxxx>
> ---
>
> Version 1 was still missing some locks around wlseg and clseg.
>
> My testing hasn't been able to reproduce the oops now for over 4 hours of
> iozone runs on two different setups. I'll keep testing...
>
> I'm not sure if this is something we want to CC to stable, AFAIK no
> vendors currently support filelayout with commit (which is why this
> codepath is seemingly untested).
>
> fs/nfs/nfs4filelayout.c | 20 ++++++++++++++++----
> 1 file changed, 16 insertions(+), 4 deletions(-)
>
> diff --git a/fs/nfs/nfs4filelayout.c b/fs/nfs/nfs4filelayout.c
> index b9a35c0..b6fc8c1 100644
> --- a/fs/nfs/nfs4filelayout.c
> +++ b/fs/nfs/nfs4filelayout.c
> @@ -1067,6 +1067,7 @@ filelayout_choose_commit_list(struct nfs_page *req,
> */
> j = nfs4_fl_calc_j_index(lseg, req_offset(req));
> i = select_bucket_index(fl, j);
> + spin_lock(cinfo->lock);
> buckets = cinfo->ds->buckets;
> list = &buckets[i].written;
> if (list_empty(list)) {
> @@ -1080,6 +1081,7 @@ filelayout_choose_commit_list(struct nfs_page *req,
> }
> set_bit(PG_COMMIT_TO_DS, &req->wb_flags);
^^ I suppose this could be moved out of the spin lock.
> cinfo->ds->nwritten++;
> + spin_unlock(cinfo->lock);
> return list;
> }
>
> @@ -1176,6 +1178,7 @@ transfer_commit_list(struct list_head *src, struct list_head *dst,
> return ret;
> }
>
> +/* Note called with cinfo->lock held. */
> static int
> filelayout_scan_ds_commit_list(struct pnfs_commit_bucket *bucket,
> struct nfs_commit_info *cinfo,
> @@ -1220,15 +1223,18 @@ static void filelayout_recover_commit_reqs(struct list_head *dst,
> struct nfs_commit_info *cinfo)
> {
> struct pnfs_commit_bucket *b;
> + struct pnfs_layout_segment *freeme;
> int i;
>
> +restart:
> spin_lock(cinfo->lock);
> for (i = 0, b = cinfo->ds->buckets; i < cinfo->ds->nbuckets; i++, b++) {
> if (transfer_commit_list(&b->written, dst, cinfo, 0)) {
> - spin_unlock(cinfo->lock);
> - pnfs_put_lseg(b->wlseg);
> + freeme = b->wlseg;
> b->wlseg = NULL;
> - spin_lock(cinfo->lock);
> + spin_unlock(cinfo->lock);
> + pnfs_put_lseg(freeme);
> + goto restart;
> }
> }
> cinfo->ds->nwritten = 0;
> @@ -1243,6 +1249,7 @@ alloc_ds_commits(struct nfs_commit_info *cinfo, struct list_head *list)
> struct nfs_commit_data *data;
> int i, j;
> unsigned int nreq = 0;
> + struct pnfs_layout_segment *freeme;
>
> fl_cinfo = cinfo->ds;
> bucket = fl_cinfo->buckets;
> @@ -1253,8 +1260,10 @@ alloc_ds_commits(struct nfs_commit_info *cinfo, struct list_head *list)
> if (!data)
> break;
> data->ds_commit_index = i;
> + spin_lock(cinfo->lock);
> data->lseg = bucket->clseg;
> bucket->clseg = NULL;
> + spin_unlock(cinfo->lock);
> list_add(&data->pages, list);
> nreq++;
> }
> @@ -1264,8 +1273,11 @@ alloc_ds_commits(struct nfs_commit_info *cinfo, struct list_head *list)
> if (list_empty(&bucket->committing))
> continue;
> nfs_retry_commit(&bucket->committing, bucket->clseg, cinfo);
> - pnfs_put_lseg(bucket->clseg);
> + spin_lock(cinfo->lock);
> + freeme = bucket->clseg;
> bucket->clseg = NULL;
> + spin_unlock(cinfo->lock);
> + pnfs_put_lseg(freeme);
> }
> /* Caller will clean up entries put on list */
> return nreq;
> --
> 1.8.5.2 (Apple Git-48)
>
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