> On Jun 22, 2022, at 2:36 PM, Wang Yugui <wangyugui@xxxxxxxxxxxx> wrote: > > Hi, > > fstests generic/531 triggered a panic on kernel 5.19.0-rc3 with this > patchset. As I mention in the cover letter, I haven't tried running generic/531 yet -- no claim at all that this is finished work and that #386 has been fixed at this point. I'm merely interested in comments on the general approach. > [ 405.478056] BUG: kernel NULL pointer dereference, address: 0000000000000049 The "RIP: " tells the location of the crash. Notice that the call trace here does not include that information. From your attachment: [ 405.518022] RIP: 0010:nfsd_do_file_acquire+0x4e1/0xb80 [nfsd] To match that to a line of source code: [cel@manet ~]$ cd src/linux/linux/ [cel@manet linux]$ scripts/faddr2line ../obj/manet/fs/nfsd/filecache.o nfsd_do_file_acquire+0x4e1 nfsd_do_file_acquire+0x4e1/0xfc0: rht_bucket_insert at /home/cel/src/linux/linux/include/linux/rhashtable.h:303 (inlined by) __rhashtable_insert_fast at /home/cel/src/linux/linux/include/linux/rhashtable.h:718 (inlined by) rhashtable_lookup_get_insert_key at /home/cel/src/linux/linux/include/linux/rhashtable.h:982 (inlined by) nfsd_file_insert at /home/cel/src/linux/linux/fs/nfsd/filecache.c:1031 (inlined by) nfsd_do_file_acquire at /home/cel/src/linux/linux/fs/nfsd/filecache.c:1089 [cel@manet linux]$ This is an example, I'm sure my compiled objects don't match yours. And, now that I've added observability, you should be able to do: # watch cat /proc/fs/nfsd/filecache to see how many items are in the hash and LRU list while the test is running. > [ 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 / $nr_cpus / 2 )) Changed from: max_allowable_files=$(( $(cat /proc/sys/fs/file-max) / $nr_cpus / 2 )) For my own information, what's $nr_cpus in your test? Aside from the max_allowable_files setting, can you tell how the test determines when it should stop creating files? Is it looking for a particular error code from open(2), for instance? On my client: [cel@morisot generic]$ cat /proc/sys/fs/file-max 9223372036854775807 [cel@morisot generic]$ I wonder if it's realistic to expect an NFSv4 server to support that many open files. Is 9 quintillion files really something I'm going to have to engineer for, or is this just a crazy test? > Best Regards > Wang Yugui (wangyugui@xxxxxxxxxxxx) > 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 > > <531.dmesg> -- Chuck Lever
