netdev - Re: [PATCH RFC 00/30] Overhaul NFSD filecache

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Message-Id: <20220623023645.F914.409509F4@e16-tech.com>
Date:   Thu, 23 Jun 2022 02:36:45 +0800
From:   Wang Yugui <wangyugui@...-tech.com>
To:     Chuck Lever <chuck.lever@...cle.com>
Cc:     linux-nfs@...r.kernel.org, netdev@...r.kernel.org,
        david@...morbit.com, tgraf@...g.ch, jlayton@...hat.com
Subject: Re: [PATCH RFC 00/30] Overhaul NFSD filecache

Hi,

fstests generic/531 triggered a panic on kernel 5.19.0-rc3 with this
patchset.

[  405.478056] BUG: kernel NULL pointer dereference, address: 0000000000000049

[  405.608016] Call Trace:
[  405.608016]  <TASK>
[  405.613020]  nfs4_get_vfs_file+0x325/0x410 [nfsd]
[  405.618018]  nfsd4_process_open2+0x4ba/0x16d0 [nfsd]
[  405.623016]  ? inode_get_bytes+0x38/0x40
[  405.623016]  ? nfsd_permission+0x97/0xf0 [nfsd]
[  405.628022]  ? fh_verify+0x1cc/0x6f0 [nfsd]
[  405.633025]  nfsd4_open+0x640/0xb30 [nfsd]
[  405.638025]  nfsd4_proc_compound+0x3bd/0x710 [nfsd]
[  405.643017]  nfsd_dispatch+0x143/0x270 [nfsd]
[  405.648019]  svc_process_common+0x3bf/0x5b0 [sunrpc]

more detail in attachment file(531.dmesg)

local.config of fstests:
	export NFS_MOUNT_OPTIONS="-o rw,relatime,vers=4.2,nconnect=8"
changes of generic/531
	max_allowable_files=$(( 1 * 1024 * 1024 / $nr_cpus / 2 ))

Best Regards
Wang Yugui (wangyugui@...-tech.com)
2022/06/23

> This series overhauls the NFSD filecache, a cache of server-side
> "struct file" objects recently used by NFS clients. The purposes of
> this overhaul are an immediate improvement in cache scalability in
> the number of open files, and preparation for further improvements.
> 
> There are three categories of patches in this series:
> 
> 1. Add observability of cache operation so we can see what we're
> doing as changes are made to the code.
> 
> 2. Improve the scalability of filecache garbage collection,
> addressing several bugs along the way.
> 
> 3. Improve the scalability of the filecache hash table by converting
> it to use rhashtable.
> 
> The series as it stands survives typical test workloads. Running
> stress-tests like generic/531 is the next step.
> 
> These patches are also available in the linux-nfs-bugzilla-386
> branch of
> 
>   https://git.kernel.org/pub/scm/linux/kernel/git/cel/linux.git 
> 
> ---
> 
> Chuck Lever (30):
>       NFSD: Report filecache LRU size
>       NFSD: Report count of calls to nfsd_file_acquire()
>       NFSD: Report count of freed filecache items
>       NFSD: Report average age of filecache items
>       NFSD: Add nfsd_file_lru_dispose_list() helper
>       NFSD: Refactor nfsd_file_gc()
>       NFSD: Refactor nfsd_file_lru_scan()
>       NFSD: Report the number of items evicted by the LRU walk
>       NFSD: Record number of flush calls
>       NFSD: Report filecache item construction failures
>       NFSD: Zero counters when the filecache is re-initialized
>       NFSD: Hook up the filecache stat file
>       NFSD: WARN when freeing an item still linked via nf_lru
>       NFSD: Trace filecache LRU activity
>       NFSD: Leave open files out of the filecache LRU
>       NFSD: Fix the filecache LRU shrinker
>       NFSD: Never call nfsd_file_gc() in foreground paths
>       NFSD: No longer record nf_hashval in the trace log
>       NFSD: Remove lockdep assertion from unhash_and_release_locked()
>       NFSD: nfsd_file_unhash can compute hashval from nf->nf_inode
>       NFSD: Refactor __nfsd_file_close_inode()
>       NFSD: nfsd_file_hash_remove can compute hashval
>       NFSD: Remove nfsd_file::nf_hashval
>       NFSD: Remove stale comment from nfsd_file_acquire()
>       NFSD: Clean up "open file" case in nfsd_file_acquire()
>       NFSD: Document nfsd_file_cache_purge() API contract
>       NFSD: Replace the "init once" mechanism
>       NFSD: Set up an rhashtable for the filecache
>       NFSD: Convert the filecache to use rhashtable
>       NFSD: Clean up unusued code after rhashtable conversion
> 
> 
>  fs/nfsd/filecache.c | 677 +++++++++++++++++++++++++++-----------------
>  fs/nfsd/filecache.h |   6 +-
>  fs/nfsd/nfsctl.c    |  10 +
>  fs/nfsd/trace.h     | 117 ++++++--
>  4 files changed, 522 insertions(+), 288 deletions(-)
> 
> --
> Chuck Lever


Download attachment "531.dmesg" of type "application/octet-stream" (55461 bytes)