Hi Chuck,
While doing some testing today with pynfs on a branch based on your
nfsd-next branch. I'm not sure which test triggers it, but it's one of
the v4.0 tests. It only takes a few mins before it crashes:
Jul 19 19:22:43 kdevops-nfsd kernel: BUG: unable to handle page fault for address: ffffd8442d049108
Jul 19 19:22:43 kdevops-nfsd kernel: #PF: supervisor read access in kernel mode
Jul 19 19:22:43 kdevops-nfsd kernel: #PF: error_code(0x0000) - not-present page
Jul 19 19:22:43 kdevops-nfsd kernel: PGD 0 P4D 0
Jul 19 19:22:43 kdevops-nfsd kernel: Oops: 0000 [#1] PREEMPT SMP PTI
Jul 19 19:22:43 kdevops-nfsd kernel: CPU: 0 PID: 743 Comm: nfsd Not tainted 6.5.0-rc2+ #19
Jul 19 19:22:43 kdevops-nfsd kernel: Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-1.fc38 04/01/2014
Jul 19 19:22:43 kdevops-nfsd kernel: RIP: 0010:kfree+0x4b/0x110
Jul 19 19:22:43 kdevops-nfsd kernel: Code: 80 48 01 d8 0f 82 d8 00 00 00 48 c7 c2 00 00 00 80 48 2b 15 9f d7 fb 00 48 01 d0 48 c1 e8 0c 48 c1 e0 06 48 03 05 7d d7 fb 00 <48> 8b 50 08 48 89 c7 f6 c2 01 0f 85 9f 00 00 >
Jul 19 19:22:43 kdevops-nfsd kernel: RSP: 0018:ffffb0858661bdc0 EFLAGS: 00010286
Jul 19 19:22:43 kdevops-nfsd kernel: RAX: ffffd8442d049100 RBX: 0000000081244052 RCX: ffff8a665e003008
Jul 19 19:22:43 kdevops-nfsd kernel: RDX: 0000759a40000000 RSI: ffffffffc0b13a45 RDI: 0000000081244052
Jul 19 19:22:43 kdevops-nfsd kernel: RBP: ffffb0858661be40 R08: ffff8a665e003008 R09: ffffffff8ebdc4ec
Jul 19 19:22:43 kdevops-nfsd kernel: R10: 000000000000000e R11: 000000000000001b R12: ffff8a6656f20150
Jul 19 19:22:43 kdevops-nfsd kernel: R13: ffff8a665e003008 R14: ffff8a6656f20100 R15: ffff8a6656f20980
Jul 19 19:22:43 kdevops-nfsd kernel: FS: 0000000000000000(0000) GS:ffff8a67bfc00000(0000) knlGS:0000000000000000
Jul 19 19:22:43 kdevops-nfsd kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Jul 19 19:22:43 kdevops-nfsd kernel: CR2: ffffd8442d049108 CR3: 0000000277e1a001 CR4: 0000000000060ef0
Jul 19 19:22:43 kdevops-nfsd kernel: Call Trace:
Jul 19 19:22:43 kdevops-nfsd kernel: <TASK>
Jul 19 19:22:43 kdevops-nfsd kernel: ? __die+0x1f/0x70
Jul 19 19:22:43 kdevops-nfsd kernel: ? page_fault_oops+0x159/0x450
Jul 19 19:22:43 kdevops-nfsd kernel: ? fixup_exception+0x22/0x310
Jul 19 19:22:43 kdevops-nfsd kernel: ? exc_page_fault+0x157/0x180
Jul 19 19:22:43 kdevops-nfsd kernel: ? asm_exc_page_fault+0x22/0x30
Jul 19 19:22:43 kdevops-nfsd kernel: ? nfsd_cache_lookup+0x3c5/0x770 [nfsd]
Jul 19 19:22:43 kdevops-nfsd kernel: ? kfree+0x4b/0x110
Jul 19 19:22:43 kdevops-nfsd kernel: nfsd_cache_lookup+0x3c5/0x770 [nfsd]
Jul 19 19:22:43 kdevops-nfsd kernel: ? __pfx_nfsd+0x10/0x10 [nfsd]
Jul 19 19:22:43 kdevops-nfsd kernel: nfsd_dispatch+0x62/0x1b0 [nfsd]
Jul 19 19:22:43 kdevops-nfsd kernel: svc_process_common+0x3cb/0x6c0 [sunrpc]
Jul 19 19:22:43 kdevops-nfsd kernel: ? __pfx_nfsd_dispatch+0x10/0x10 [nfsd]
Jul 19 19:22:43 kdevops-nfsd kernel: ? __pfx_nfsd+0x10/0x10 [nfsd]
Jul 19 19:22:43 kdevops-nfsd kernel: svc_process+0x12d/0x170 [sunrpc]
Jul 19 19:22:43 kdevops-nfsd kernel: nfsd+0xd5/0x1a0 [nfsd]
Jul 19 19:22:43 kdevops-nfsd kernel: kthread+0xf3/0x120
Jul 19 19:22:43 kdevops-nfsd kernel: ? __pfx_kthread+0x10/0x10
Jul 19 19:22:43 kdevops-nfsd kernel: ret_from_fork+0x30/0x50
Jul 19 19:22:43 kdevops-nfsd kernel: ? __pfx_kthread+0x10/0x10
Jul 19 19:22:43 kdevops-nfsd kernel: ret_from_fork_asm+0x1b/0x30
Jul 19 19:22:43 kdevops-nfsd kernel: RIP: 0000:0x0
Jul 19 19:22:43 kdevops-nfsd kernel: Code: Unable to access opcode bytes at 0xffffffffffffffd6.
Jul 19 19:22:43 kdevops-nfsd kernel: RSP: 0000:0000000000000000 EFLAGS: 00000000 ORIG_RAX: 0000000000000000
Jul 19 19:22:43 kdevops-nfsd kernel: RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
Jul 19 19:22:43 kdevops-nfsd kernel: RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
Jul 19 19:22:43 kdevops-nfsd kernel: RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
Jul 19 19:22:43 kdevops-nfsd kernel: R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
Jul 19 19:22:43 kdevops-nfsd kernel: R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
Jul 19 19:22:43 kdevops-nfsd kernel: </TASK>
Jul 19 19:22:43 kdevops-nfsd kernel: Modules linked in: 9p netfs nls_iso8859_1 nls_cp437 vfat fat kvm_intel joydev kvm cirrus psmouse drm_shmem_helper irqbypass pcspkr virtio_net net_failover failover virtio_balloon >
Jul 19 19:22:43 kdevops-nfsd kernel: CR2: ffffd8442d049108
Jul 19 19:22:43 kdevops-nfsd kernel: ---[ end trace 0000000000000000 ]---
Jul 19 19:22:43 kdevops-nfsd kernel: RIP: 0010:kfree+0x4b/0x110
Jul 19 19:22:43 kdevops-nfsd kernel: Code: 80 48 01 d8 0f 82 d8 00 00 00 48 c7 c2 00 00 00 80 48 2b 15 9f d7 fb 00 48 01 d0 48 c1 e8 0c 48 c1 e0 06 48 03 05 7d d7 fb 00 <48> 8b 50 08 48 89 c7 f6 c2 01 0f 85 9f 00 00 >
Jul 19 19:22:43 kdevops-nfsd kernel: RSP: 0018:ffffb0858661bdc0 EFLAGS: 00010286
Jul 19 19:22:43 kdevops-nfsd kernel: RAX: ffffd8442d049100 RBX: 0000000081244052 RCX: ffff8a665e003008
Jul 19 19:22:43 kdevops-nfsd kernel: RDX: 0000759a40000000 RSI: ffffffffc0b13a45 RDI: 0000000081244052
Jul 19 19:22:43 kdevops-nfsd kernel: RBP: ffffb0858661be40 R08: ffff8a665e003008 R09: ffffffff8ebdc4ec
Jul 19 19:22:43 kdevops-nfsd kernel: R10: 000000000000000e R11: 000000000000001b R12: ffff8a6656f20150
Jul 19 19:22:43 kdevops-nfsd kernel: R13: ffff8a665e003008 R14: ffff8a6656f20100 R15: ffff8a6656f20980
Jul 19 19:22:43 kdevops-nfsd kernel: FS: 0000000000000000(0000) GS:ffff8a67bfc00000(0000) knlGS:0000000000000000
Jul 19 19:22:43 kdevops-nfsd kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Jul 19 19:22:43 kdevops-nfsd kernel: CR2: ffffffffffffffd6 CR3: 0000000277e1a001 CR4: 0000000000060ef0
Jul 19 19:22:43 kdevops-nfsd kernel: note: nfsd[743] exited with irqs disabled
Jul 19 19:22:43 kdevops-nfsd kernel: note: nfsd[743] exited with preempt_count 1
faddr2line says:
$ ./scripts/faddr2line --list fs/nfsd/nfsd.ko nfsd_cache_lookup+0x3c5/0x770
nfsd_cacherep_free at /home/jlayton/git/kdevops/linux/fs/nfsd/nfscache.c:116
111 }
112
113 static void nfsd_cacherep_free(struct nfsd_cacherep *rp)
114 {
115 kfree(rp->c_replvec.iov_base);
>116< kmem_cache_free(drc_slab, rp);
117 }
118
119 static unsigned long
120 nfsd_cacherep_dispose(struct list_head *dispose)
121 {
(inlined by) nfsd_reply_cache_free_locked at /home/jlayton/git/kdevops/linux/fs/nfsd/nfscache.c:153
148 static void
149 nfsd_reply_cache_free_locked(struct nfsd_drc_bucket *b, struct nfsd_cacherep *rp,
150 struct nfsd_net *nn)
151 {
152 nfsd_cacherep_unlink_locked(nn, b, rp);
>153< nfsd_cacherep_free(rp);
154 }
155
156 static void
157 nfsd_reply_cache_free(struct nfsd_drc_bucket *b, struct nfsd_cacherep *rp,
158 struct nfsd_net *nn)
(inlined by) nfsd_cache_lookup at /home/jlayton/git/kdevops/linux/fs/nfsd/nfscache.c:527
522 nfsd_stats_drc_mem_usage_add(nn, sizeof(*rp));
523 goto out;
524
525 found_entry:
526 /* We found a matching entry which is either in progress or done. */
>527< nfsd_reply_cache_free_locked(NULL, rp, nn);
528 nfsd_stats_rc_hits_inc();
529 rtn = RC_DROPIT;
530 rp = found;
531
532 /* Request being processed */
...and a bisect landed here:
767b1d5badd6eb418e3f91f0cd8fa6d2894ff43a is the first bad commit
commit 767b1d5badd6eb418e3f91f0cd8fa6d2894ff43a
Author: Chuck Lever <chuck.lever@xxxxxxxxxx>
Date: Sun Jul 9 11:45:16 2023 -0400
NFSD: Refactor nfsd_reply_cache_free_locked()
To reduce contention on the bucket locks, we must avoid calling
kfree() while each bucket lock is held.
Start by refactoring nfsd_reply_cache_free_locked() into a helper
that removes an entry from the bucket (and must therefore run under
the lock) and a second helper that frees the entry (which does not
need to hold the lock).
For readability, rename the helpers nfsd_cacherep_<verb>.
Reviewed-by: Jeff Layton <jlayton@xxxxxxxxxx>
Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx>
fs/nfsd/nfscache.c | 26 +++++++++++++++++++-------
1 file changed, 19 insertions(+), 7 deletions(-)
--
Jeff Layton <jlayton@xxxxxxxxxx>
