nfsd_file_cache_purge is called when the server is shutting down, in
which case, tearing things down is generally fine, but it also gets
called when the exports cache is flushed.
Instead of walking the cache and freeing everything unconditionally,
attempt to unhash each entry and get a reference to it, and then put
that reference. Only queue it to the dispose list if the refcount goes
to 0.
Fixes: ac3a2585f018 ("nfsd: rework refcounting in filecache")
Reported-by: Ruben Vestergaard <[email protected]>
Reported-by: Torkil Svensgaard <[email protected]>
Reported-by: Shachar Kagan <[email protected]>
Signed-off-by: Jeffrey Layton <[email protected]>
---
fs/nfsd/filecache.c | 21 ++++++++++++++++++---
1 file changed, 18 insertions(+), 3 deletions(-)
I was able to reproduce this today by running pynfs against the server
while running "exportfs -ra" in a loop. This one is a bit different in
that it happened in the open codepath, but that's probably just because
delegations are more likely to be long-lived. With this patch, the
server survives the run:
[ 337.962027] ------------[ cut here ]------------
[ 337.963823] refcount_t: underflow; use-after-free.
[ 337.965502] WARNING: CPU: 6 PID: 3401 at lib/refcount.c:28 refcount_warn_saturate+0xba/0x110
[ 337.967999] Modules linked in: nfsd(E) auth_rpcgss(E) nfs_acl(E) lockd(E) grace(E) sunrpc(E) nls_iso8859_1(E) nls_cp437(E) vfat(E) fat(E) ext4(E) crc16(E) cirrus(E) kvm_intel(E) 9p(E) mbcache(E) joydev(E) virtio_net(E) drm_shmem_helper(E) net_failover(E) kvm(E) jbd2(E) netfs(E) psmouse(E) evdev(E) pcspkr(E) failover(E) irqbypass(E) virtio_balloon(E) drm_kms_helper(E) 9pnet_virtio(E) button(E) drm(E) configfs(E) zram(E) zsmalloc(E) crct10dif_pclmul(E) crc32_pclmul(E) nvme(E) ghash_clmulni_intel(E) virtio_blk(E) sha512_ssse3(E) sha512_generic(E) nvme_core(E) t10_pi(E) virtio_pci(E) virtio(E) crc64_rocksoft_generic(E) aesni_intel(E) crypto_simd(E) crc64_rocksoft(E) virtio_pci_legacy_dev(E) i6300esb(E) cryptd(E) serio_raw(E) crc64(E) virtio_pci_modern_dev(E) virtio_ring(E) btrfs(E) blake2b_generic(E) xor(E) raid6_pq(E) libcrc32c(E) crc32c_generic(E) crc32c_intel(E) autofs4(E)
[ 337.992040] CPU: 6 PID: 3401 Comm: nfsd Tainted: G E 6.2.0-rc3+ #11
[ 337.994701] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.1-2.fc37 04/01/2014
[ 337.998046] RIP: 0010:refcount_warn_saturate+0xba/0x110
[ 337.999852] Code: 01 01 e8 83 e5 4f 00 0f 0b c3 cc cc cc cc 80 3d 60 f4 05 01 00 75 85 48 c7 c7 30 b5 e1 9d c6 05 50 f4 05 01 01 e8 60 e5 4f 00 <0f> 0b c3 cc cc cc cc 80 3d 3b f4 05 01 00 0f 85 5e ff ff ff 48 c7
[ 338.005245] RSP: 0018:ffffa36802e4bd50 EFLAGS: 00010282
[ 338.006621] RAX: 0000000000000000 RBX: 0000000000000008 RCX: 0000000000000000
[ 338.008273] RDX: 0000000000000001 RSI: ffffffff9de03ef5 RDI: 00000000ffffffff
[ 338.009804] RBP: 0000000000000003 R08: 0000000000000000 R09: ffffa36802e4bc00
[ 338.011719] R10: 0000000000000003 R11: ffffffff9e0bfdc8 R12: ffff9578da461b80
[ 338.013533] R13: 0000000000000001 R14: ffff9578da422280 R15: ffff9578da461b80
[ 338.015238] FS: 0000000000000000(0000) GS:ffff957a37d00000(0000) knlGS:0000000000000000
[ 338.017179] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 338.018680] CR2: 00007f324c1e1c08 CR3: 000000020360a004 CR4: 0000000000060ee0
[ 338.020377] Call Trace:
[ 338.021190] <TASK>
[ 338.021956] release_all_access+0x96/0x120 [nfsd]
[ 338.023192] ? _raw_spin_unlock+0x15/0x30
[ 338.024192] nfsd4_close+0x275/0x3d0 [nfsd]
[ 338.025468] ? fh_verify+0x45e/0x780 [nfsd]
[ 338.027535] ? __pfx_nfsd4_encode_noop+0x10/0x10 [nfsd]
[ 338.028775] ? nfsd4_encode_operation+0xae/0x280 [nfsd]
[ 338.030593] nfsd4_proc_compound+0x3ae/0x6f0 [nfsd]
[ 338.032341] nfsd_dispatch+0x16a/0x270 [nfsd]
[ 338.034667] svc_process_common+0x2eb/0x660 [sunrpc]
[ 338.036614] ? __pfx_nfsd_dispatch+0x10/0x10 [nfsd]
[ 338.038827] ? __pfx_nfsd+0x10/0x10 [nfsd]
[ 338.040267] svc_process+0xad/0x100 [sunrpc]
[ 338.041981] nfsd+0xd5/0x190 [nfsd]
[ 338.043362] kthread+0xe9/0x110
[ 338.044680] ? __pfx_kthread+0x10/0x10
[ 338.046376] ret_from_fork+0x2c/0x50
[ 338.047892] </TASK>
[ 338.049067] ---[ end trace 0000000000000000 ]---
[ 760.792789] BUG: kernel NULL pointer dereference, address: 0000000000000078
[ 760.795933] #PF: supervisor read access in kernel mode
[ 760.797477] #PF: error_code(0x0000) - not-present page
[ 760.799120] PGD 0 P4D 0
[ 760.800140] Oops: 0000 [#1] PREEMPT SMP PTI
[ 760.801383] CPU: 2 PID: 3401 Comm: nfsd Tainted: G W E 6.2.0-rc3+ #11
[ 760.803120] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.1-2.fc37 04/01/2014
[ 760.805018] RIP: 0010:filp_close+0x23/0x70
[ 760.806099] Code: 90 90 90 90 90 90 90 0f 1f 44 00 00 41 54 55 53 48 8b 47 38 48 85 c0 0f 84 41 e1 6d 00 48 8b 47 28 48 89 fb 48 89 f5 45 31 e4 <48> 8b 40 78 48 85 c0 74 08 e8 6f 70 72 00 41 89 c4 f6 43 45 40 75
[ 760.809737] RSP: 0018:ffffa36802e4bc78 EFLAGS: 00010246
[ 760.811084] RAX: 0000000000000000 RBX: ffff9578c7d4d600 RCX: 0000000000000000
[ 760.812540] RDX: 000000000000098d RSI: 0000000000000000 RDI: ffff9578c7d4d600
[ 760.814433] RBP: 0000000000000000 R08: 0000011335048e60 R09: ffff9578f82f1540
[ 760.816089] R10: ffffa36802e4bcd0 R11: ffffa36802e4bcd8 R12: 0000000000000000
[ 760.817529] R13: 0000000000000001 R14: dead000000000100 R15: ffff9578f82f1558
[ 760.818982] FS: 0000000000000000(0000) GS:ffff957a37c80000(0000) knlGS:0000000000000000
[ 760.820544] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 760.821734] CR2: 0000000000000078 CR3: 00000001565ce002 CR4: 0000000000060ee0
[ 760.823141] Call Trace:
[ 760.823808] <TASK>
[ 760.824419] nfsd_file_free+0xe9/0x210 [nfsd]
[ 760.825610] release_all_access+0x96/0x120 [nfsd]
[ 760.826680] nfs4_free_ol_stateid+0x22/0x60 [nfsd]
[ 760.827747] free_ol_stateid_reaplist+0x61/0x90 [nfsd]
[ 760.828858] release_openowner+0x258/0x2a0 [nfsd]
[ 760.829792] __destroy_client+0x183/0x290 [nfsd]
[ 760.830694] nfsd4_setclientid_confirm+0x1a3/0x4f0 [nfsd]
[ 760.831763] nfsd4_proc_compound+0x3ae/0x6f0 [nfsd]
[ 760.832717] nfsd_dispatch+0x16a/0x270 [nfsd]
[ 760.833576] svc_process_common+0x2eb/0x660 [sunrpc]
[ 760.834587] ? __pfx_nfsd_dispatch+0x10/0x10 [nfsd]
[ 760.835576] ? __pfx_nfsd+0x10/0x10 [nfsd]
[ 760.836462] svc_process+0xad/0x100 [sunrpc]
[ 760.837317] nfsd+0xd5/0x190 [nfsd]
[ 760.838133] kthread+0xe9/0x110
[ 760.838862] ? __pfx_kthread+0x10/0x10
[ 760.839755] ret_from_fork+0x2c/0x50
[ 760.840534] </TASK>
[ 760.841167] Modules linked in: nfsd(E) auth_rpcgss(E) nfs_acl(E) lockd(E) grace(E) sunrpc(E) nls_iso8859_1(E) nls_cp437(E) vfat(E) fat(E) ext4(E) crc16(E) cirrus(E) kvm_intel(E) 9p(E) mbcache(E) joydev(E) virtio_net(E) drm_shmem_helper(E) net_failover(E) kvm(E) jbd2(E) netfs(E) psmouse(E) evdev(E) pcspkr(E) failover(E) irqbypass(E) virtio_balloon(E) drm_kms_helper(E) 9pnet_virtio(E) button(E) drm(E) configfs(E) zram(E) zsmalloc(E) crct10dif_pclmul(E) crc32_pclmul(E) nvme(E) ghash_clmulni_intel(E) virtio_blk(E) sha512_ssse3(E) sha512_generic(E) nvme_core(E) t10_pi(E) virtio_pci(E) virtio(E) crc64_rocksoft_generic(E) aesni_intel(E) crypto_simd(E) crc64_rocksoft(E) virtio_pci_legacy_dev(E) i6300esb(E) cryptd(E) serio_raw(E) crc64(E) virtio_pci_modern_dev(E) virtio_ring(E) btrfs(E) blake2b_generic(E) xor(E) raid6_pq(E) libcrc32c(E) crc32c_generic(E) crc32c_intel(E) autofs4(E)
[ 760.853527] CR2: 0000000000000078
[ 760.854340] ---[ end trace 0000000000000000 ]---
[ 760.855261] RIP: 0010:filp_close+0x23/0x70
[ 760.856185] Code: 90 90 90 90 90 90 90 0f 1f 44 00 00 41 54 55 53 48 8b 47 38 48 85 c0 0f 84 41 e1 6d 00 48 8b 47 28 48 89 fb 48 89 f5 45 31 e4 <48> 8b 40 78 48 85 c0 74 08 e8 6f 70 72 00 41 89 c4 f6 43 45 40 75
[ 760.859350] RSP: 0018:ffffa36802e4bc78 EFLAGS: 00010246
[ 760.860356] RAX: 0000000000000000 RBX: ffff9578c7d4d600 RCX: 0000000000000000
[ 760.861628] RDX: 000000000000098d RSI: 0000000000000000 RDI: ffff9578c7d4d600
[ 760.862898] RBP: 0000000000000000 R08: 0000011335048e60 R09: ffff9578f82f1540
[ 760.864172] R10: ffffa36802e4bcd0 R11: ffffa36802e4bcd8 R12: 0000000000000000
[ 760.865438] R13: 0000000000000001 R14: dead000000000100 R15: ffff9578f82f1558
[ 760.866692] FS: 0000000000000000(0000) GS:ffff957a37c80000(0000) knlGS:0000000000000000
[ 760.868053] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 760.869102] CR2: 0000000000000078 CR3: 00000001565ce002 CR4: 0000000000060ee0
diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
index 66449c41b19c..b9100707d347 100644
--- a/fs/nfsd/filecache.c
+++ b/fs/nfsd/filecache.c
@@ -908,9 +908,24 @@ __nfsd_file_cache_purge(struct net *net)
nf = rhashtable_walk_next(&iter);
while (!IS_ERR_OR_NULL(nf)) {
if (!net || nf->nf_net == net) {
- nfsd_file_unhash(nf);
- nfsd_file_lru_remove(nf);
- list_add(&nf->nf_lru, &dispose);
+ /* Ignore it if it's no longer hashed */
+ if (!nfsd_file_unhash(nf))
+ continue;
+
+ /*
+ * Try to claim the LRU ref (if any). If it's
+ * not on the LRU, then try to take a ref. If that
+ * fails, then we'll ignore it.
+ */
+ if (!nfsd_file_lru_remove(nf))
+ nf = nfsd_file_get(nf);
+
+ /*
+ * Now try to put the ref we hold. If that works
+ * and it goes to zero, queue it to be freed.
+ */
+ if (nf && refcount_dec_and_test(&nf->nf_ref))
+ list_add(&nf->nf_lru, &dispose);
}
nf = rhashtable_walk_next(&iter);
}
--
2.39.0
On Thu, 2023-01-19 at 22:59 +0000, Chuck Lever III wrote:
>
> > On Jan 19, 2023, at 2:20 PM, Jeff Layton <[email protected]> wrote:
> >
> > nfsd_file_cache_purge is called when the server is shutting down, in
> > which case, tearing things down is generally fine, but it also gets
> > called when the exports cache is flushed.
> >
> > Instead of walking the cache and freeing everything unconditionally,
> > attempt to unhash each entry and get a reference to it, and then put
> > that reference. Only queue it to the dispose list if the refcount goes
> > to 0.
> >
> > Fixes: ac3a2585f018 ("nfsd: rework refcounting in filecache")
> > Reported-by: Ruben Vestergaard <[email protected]>
> > Reported-by: Torkil Svensgaard <[email protected]>
> > Reported-by: Shachar Kagan <[email protected]>
> > Signed-off-by: Jeffrey Layton <[email protected]>
>
> FYI, checkpatch complained that the Signed-off-by does not
> exactly match the From: address. I haven't see "Jeffrey"
> before, but the DKIM check passed, so....
>
> .... I've applied this to nfsd-fixes (formerly for-rc).
>
Whoops! I originally did this in a different tree and had to fix up the
Sob line. Let's change it to "Jeff" if it makes checkpatch happy. Thanks
for pulling it in quickly!
>
> > ---
> > fs/nfsd/filecache.c | 21 ++++++++++++++++++---
> > 1 file changed, 18 insertions(+), 3 deletions(-)
> >
> > I was able to reproduce this today by running pynfs against the server
> > while running "exportfs -ra" in a loop. This one is a bit different in
> > that it happened in the open codepath, but that's probably just because
> > delegations are more likely to be long-lived. With this patch, the
> > server survives the run:
> >
> > [ 337.962027] ------------[ cut here ]------------
> > [ 337.963823] refcount_t: underflow; use-after-free.
> > [ 337.965502] WARNING: CPU: 6 PID: 3401 at lib/refcount.c:28 refcount_warn_saturate+0xba/0x110
> > [ 337.967999] Modules linked in: nfsd(E) auth_rpcgss(E) nfs_acl(E) lockd(E) grace(E) sunrpc(E) nls_iso8859_1(E) nls_cp437(E) vfat(E) fat(E) ext4(E) crc16(E) cirrus(E) kvm_intel(E) 9p(E) mbcache(E) joydev(E) virtio_net(E) drm_shmem_helper(E) net_failover(E) kvm(E) jbd2(E) netfs(E) psmouse(E) evdev(E) pcspkr(E) failover(E) irqbypass(E) virtio_balloon(E) drm_kms_helper(E) 9pnet_virtio(E) button(E) drm(E) configfs(E) zram(E) zsmalloc(E) crct10dif_pclmul(E) crc32_pclmul(E) nvme(E) ghash_clmulni_intel(E) virtio_blk(E) sha512_ssse3(E) sha512_generic(E) nvme_core(E) t10_pi(E) virtio_pci(E) virtio(E) crc64_rocksoft_generic(E) aesni_intel(E) crypto_simd(E) crc64_rocksoft(E) virtio_pci_legacy_dev(E) i6300esb(E) cryptd(E) serio_raw(E) crc64(E) virtio_pci_modern_dev(E) virtio_ring(E) btrfs(E) blake2b_generic(E) xor(E) raid6_pq(E) libcrc32c(E) crc32c_generic(E) crc32c_intel(E) autofs4(E)
> > [ 337.992040] CPU: 6 PID: 3401 Comm: nfsd Tainted: G E 6.2.0-rc3+ #11
> > [ 337.994701] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.1-2.fc37 04/01/2014
> > [ 337.998046] RIP: 0010:refcount_warn_saturate+0xba/0x110
> > [ 337.999852] Code: 01 01 e8 83 e5 4f 00 0f 0b c3 cc cc cc cc 80 3d 60 f4 05 01 00 75 85 48 c7 c7 30 b5 e1 9d c6 05 50 f4 05 01 01 e8 60 e5 4f 00 <0f> 0b c3 cc cc cc cc 80 3d 3b f4 05 01 00 0f 85 5e ff ff ff 48 c7
> > [ 338.005245] RSP: 0018:ffffa36802e4bd50 EFLAGS: 00010282
> > [ 338.006621] RAX: 0000000000000000 RBX: 0000000000000008 RCX: 0000000000000000
> > [ 338.008273] RDX: 0000000000000001 RSI: ffffffff9de03ef5 RDI: 00000000ffffffff
> > [ 338.009804] RBP: 0000000000000003 R08: 0000000000000000 R09: ffffa36802e4bc00
> > [ 338.011719] R10: 0000000000000003 R11: ffffffff9e0bfdc8 R12: ffff9578da461b80
> > [ 338.013533] R13: 0000000000000001 R14: ffff9578da422280 R15: ffff9578da461b80
> > [ 338.015238] FS: 0000000000000000(0000) GS:ffff957a37d00000(0000) knlGS:0000000000000000
> > [ 338.017179] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [ 338.018680] CR2: 00007f324c1e1c08 CR3: 000000020360a004 CR4: 0000000000060ee0
> > [ 338.020377] Call Trace:
> > [ 338.021190] <TASK>
> > [ 338.021956] release_all_access+0x96/0x120 [nfsd]
> > [ 338.023192] ? _raw_spin_unlock+0x15/0x30
> > [ 338.024192] nfsd4_close+0x275/0x3d0 [nfsd]
> > [ 338.025468] ? fh_verify+0x45e/0x780 [nfsd]
> > [ 338.027535] ? __pfx_nfsd4_encode_noop+0x10/0x10 [nfsd]
> > [ 338.028775] ? nfsd4_encode_operation+0xae/0x280 [nfsd]
> > [ 338.030593] nfsd4_proc_compound+0x3ae/0x6f0 [nfsd]
> > [ 338.032341] nfsd_dispatch+0x16a/0x270 [nfsd]
> > [ 338.034667] svc_process_common+0x2eb/0x660 [sunrpc]
> > [ 338.036614] ? __pfx_nfsd_dispatch+0x10/0x10 [nfsd]
> > [ 338.038827] ? __pfx_nfsd+0x10/0x10 [nfsd]
> > [ 338.040267] svc_process+0xad/0x100 [sunrpc]
> > [ 338.041981] nfsd+0xd5/0x190 [nfsd]
> > [ 338.043362] kthread+0xe9/0x110
> > [ 338.044680] ? __pfx_kthread+0x10/0x10
> > [ 338.046376] ret_from_fork+0x2c/0x50
> > [ 338.047892] </TASK>
> > [ 338.049067] ---[ end trace 0000000000000000 ]---
> > [ 760.792789] BUG: kernel NULL pointer dereference, address: 0000000000000078
> > [ 760.795933] #PF: supervisor read access in kernel mode
> > [ 760.797477] #PF: error_code(0x0000) - not-present page
> > [ 760.799120] PGD 0 P4D 0
> > [ 760.800140] Oops: 0000 [#1] PREEMPT SMP PTI
> > [ 760.801383] CPU: 2 PID: 3401 Comm: nfsd Tainted: G W E 6.2.0-rc3+ #11
> > [ 760.803120] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.1-2.fc37 04/01/2014
> > [ 760.805018] RIP: 0010:filp_close+0x23/0x70
> > [ 760.806099] Code: 90 90 90 90 90 90 90 0f 1f 44 00 00 41 54 55 53 48 8b 47 38 48 85 c0 0f 84 41 e1 6d 00 48 8b 47 28 48 89 fb 48 89 f5 45 31 e4 <48> 8b 40 78 48 85 c0 74 08 e8 6f 70 72 00 41 89 c4 f6 43 45 40 75
> > [ 760.809737] RSP: 0018:ffffa36802e4bc78 EFLAGS: 00010246
> > [ 760.811084] RAX: 0000000000000000 RBX: ffff9578c7d4d600 RCX: 0000000000000000
> > [ 760.812540] RDX: 000000000000098d RSI: 0000000000000000 RDI: ffff9578c7d4d600
> > [ 760.814433] RBP: 0000000000000000 R08: 0000011335048e60 R09: ffff9578f82f1540
> > [ 760.816089] R10: ffffa36802e4bcd0 R11: ffffa36802e4bcd8 R12: 0000000000000000
> > [ 760.817529] R13: 0000000000000001 R14: dead000000000100 R15: ffff9578f82f1558
> > [ 760.818982] FS: 0000000000000000(0000) GS:ffff957a37c80000(0000) knlGS:0000000000000000
> > [ 760.820544] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [ 760.821734] CR2: 0000000000000078 CR3: 00000001565ce002 CR4: 0000000000060ee0
> > [ 760.823141] Call Trace:
> > [ 760.823808] <TASK>
> > [ 760.824419] nfsd_file_free+0xe9/0x210 [nfsd]
> > [ 760.825610] release_all_access+0x96/0x120 [nfsd]
> > [ 760.826680] nfs4_free_ol_stateid+0x22/0x60 [nfsd]
> > [ 760.827747] free_ol_stateid_reaplist+0x61/0x90 [nfsd]
> > [ 760.828858] release_openowner+0x258/0x2a0 [nfsd]
> > [ 760.829792] __destroy_client+0x183/0x290 [nfsd]
> > [ 760.830694] nfsd4_setclientid_confirm+0x1a3/0x4f0 [nfsd]
> > [ 760.831763] nfsd4_proc_compound+0x3ae/0x6f0 [nfsd]
> > [ 760.832717] nfsd_dispatch+0x16a/0x270 [nfsd]
> > [ 760.833576] svc_process_common+0x2eb/0x660 [sunrpc]
> > [ 760.834587] ? __pfx_nfsd_dispatch+0x10/0x10 [nfsd]
> > [ 760.835576] ? __pfx_nfsd+0x10/0x10 [nfsd]
> > [ 760.836462] svc_process+0xad/0x100 [sunrpc]
> > [ 760.837317] nfsd+0xd5/0x190 [nfsd]
> > [ 760.838133] kthread+0xe9/0x110
> > [ 760.838862] ? __pfx_kthread+0x10/0x10
> > [ 760.839755] ret_from_fork+0x2c/0x50
> > [ 760.840534] </TASK>
> > [ 760.841167] Modules linked in: nfsd(E) auth_rpcgss(E) nfs_acl(E) lockd(E) grace(E) sunrpc(E) nls_iso8859_1(E) nls_cp437(E) vfat(E) fat(E) ext4(E) crc16(E) cirrus(E) kvm_intel(E) 9p(E) mbcache(E) joydev(E) virtio_net(E) drm_shmem_helper(E) net_failover(E) kvm(E) jbd2(E) netfs(E) psmouse(E) evdev(E) pcspkr(E) failover(E) irqbypass(E) virtio_balloon(E) drm_kms_helper(E) 9pnet_virtio(E) button(E) drm(E) configfs(E) zram(E) zsmalloc(E) crct10dif_pclmul(E) crc32_pclmul(E) nvme(E) ghash_clmulni_intel(E) virtio_blk(E) sha512_ssse3(E) sha512_generic(E) nvme_core(E) t10_pi(E) virtio_pci(E) virtio(E) crc64_rocksoft_generic(E) aesni_intel(E) crypto_simd(E) crc64_rocksoft(E) virtio_pci_legacy_dev(E) i6300esb(E) cryptd(E) serio_raw(E) crc64(E) virtio_pci_modern_dev(E) virtio_ring(E) btrfs(E) blake2b_generic(E) xor(E) raid6_pq(E) libcrc32c(E) crc32c_generic(E) crc32c_intel(E) autofs4(E)
> > [ 760.853527] CR2: 0000000000000078
> > [ 760.854340] ---[ end trace 0000000000000000 ]---
> > [ 760.855261] RIP: 0010:filp_close+0x23/0x70
> > [ 760.856185] Code: 90 90 90 90 90 90 90 0f 1f 44 00 00 41 54 55 53 48 8b 47 38 48 85 c0 0f 84 41 e1 6d 00 48 8b 47 28 48 89 fb 48 89 f5 45 31 e4 <48> 8b 40 78 48 85 c0 74 08 e8 6f 70 72 00 41 89 c4 f6 43 45 40 75
> > [ 760.859350] RSP: 0018:ffffa36802e4bc78 EFLAGS: 00010246
> > [ 760.860356] RAX: 0000000000000000 RBX: ffff9578c7d4d600 RCX: 0000000000000000
> > [ 760.861628] RDX: 000000000000098d RSI: 0000000000000000 RDI: ffff9578c7d4d600
> > [ 760.862898] RBP: 0000000000000000 R08: 0000011335048e60 R09: ffff9578f82f1540
> > [ 760.864172] R10: ffffa36802e4bcd0 R11: ffffa36802e4bcd8 R12: 0000000000000000
> > [ 760.865438] R13: 0000000000000001 R14: dead000000000100 R15: ffff9578f82f1558
> > [ 760.866692] FS: 0000000000000000(0000) GS:ffff957a37c80000(0000) knlGS:0000000000000000
> > [ 760.868053] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > [ 760.869102] CR2: 0000000000000078 CR3: 00000001565ce002 CR4: 0000000000060ee0
> >
> > diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
> > index 66449c41b19c..b9100707d347 100644
> > --- a/fs/nfsd/filecache.c
> > +++ b/fs/nfsd/filecache.c
> > @@ -908,9 +908,24 @@ __nfsd_file_cache_purge(struct net *net)
> > nf = rhashtable_walk_next(&iter);
> > while (!IS_ERR_OR_NULL(nf)) {
> > if (!net || nf->nf_net == net) {
> > - nfsd_file_unhash(nf);
> > - nfsd_file_lru_remove(nf);
> > - list_add(&nf->nf_lru, &dispose);
> > + /* Ignore it if it's no longer hashed */
> > + if (!nfsd_file_unhash(nf))
> > + continue;
> > +
> > + /*
> > + * Try to claim the LRU ref (if any). If it's
> > + * not on the LRU, then try to take a ref. If that
> > + * fails, then we'll ignore it.
> > + */
> > + if (!nfsd_file_lru_remove(nf))
> > + nf = nfsd_file_get(nf);
> > +
> > + /*
> > + * Now try to put the ref we hold. If that works
> > + * and it goes to zero, queue it to be freed.
> > + */
> > + if (nf && refcount_dec_and_test(&nf->nf_ref))
> > + list_add(&nf->nf_lru, &dispose);
> > }
> > nf = rhashtable_walk_next(&iter);
> > }
> > --
> > 2.39.0
> >
>
> --
> Chuck Lever
>
>
>
--
Jeff Layton <[email protected]>
On Thu, 2023-01-19 at 14:20 -0500, Jeff Layton wrote:
> nfsd_file_cache_purge is called when the server is shutting down, in
> which case, tearing things down is generally fine, but it also gets
> called when the exports cache is flushed.
>
> Instead of walking the cache and freeing everything unconditionally,
> attempt to unhash each entry and get a reference to it, and then put
> that reference. Only queue it to the dispose list if the refcount goes
> to 0.
>
> Fixes: ac3a2585f018 ("nfsd: rework refcounting in filecache")
> Reported-by: Ruben Vestergaard <[email protected]>
> Reported-by: Torkil Svensgaard <[email protected]>
> Reported-by: Shachar Kagan <[email protected]>
> Signed-off-by: Jeffrey Layton <[email protected]>
> ---
> fs/nfsd/filecache.c | 21 ++++++++++++++++++---
> 1 file changed, 18 insertions(+), 3 deletions(-)
>
> I was able to reproduce this today by running pynfs against the server
> while running "exportfs -ra" in a loop. This one is a bit different in
> that it happened in the open codepath, but that's probably just because
> delegations are more likely to be long-lived. With this patch, the
> server survives the run:
>
> [ 337.962027] ------------[ cut here ]------------
> [ 337.963823] refcount_t: underflow; use-after-free.
> [ 337.965502] WARNING: CPU: 6 PID: 3401 at lib/refcount.c:28 refcount_warn_saturate+0xba/0x110
> [ 337.967999] Modules linked in: nfsd(E) auth_rpcgss(E) nfs_acl(E) lockd(E) grace(E) sunrpc(E) nls_iso8859_1(E) nls_cp437(E) vfat(E) fat(E) ext4(E) crc16(E) cirrus(E) kvm_intel(E) 9p(E) mbcache(E) joydev(E) virtio_net(E) drm_shmem_helper(E) net_failover(E) kvm(E) jbd2(E) netfs(E) psmouse(E) evdev(E) pcspkr(E) failover(E) irqbypass(E) virtio_balloon(E) drm_kms_helper(E) 9pnet_virtio(E) button(E) drm(E) configfs(E) zram(E) zsmalloc(E) crct10dif_pclmul(E) crc32_pclmul(E) nvme(E) ghash_clmulni_intel(E) virtio_blk(E) sha512_ssse3(E) sha512_generic(E) nvme_core(E) t10_pi(E) virtio_pci(E) virtio(E) crc64_rocksoft_generic(E) aesni_intel(E) crypto_simd(E) crc64_rocksoft(E) virtio_pci_legacy_dev(E) i6300esb(E) cryptd(E) serio_raw(E) crc64(E) virtio_pci_modern_dev(E) virtio_ring(E) btrfs(E) blake2b_generic(E) xor(E) raid6_pq(E) libcrc32c(E) crc32c_generic(E) crc32c_intel(E) autofs4(E)
> [ 337.992040] CPU: 6 PID: 3401 Comm: nfsd Tainted: G E 6.2.0-rc3+ #11
> [ 337.994701] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.1-2.fc37 04/01/2014
> [ 337.998046] RIP: 0010:refcount_warn_saturate+0xba/0x110
> [ 337.999852] Code: 01 01 e8 83 e5 4f 00 0f 0b c3 cc cc cc cc 80 3d 60 f4 05 01 00 75 85 48 c7 c7 30 b5 e1 9d c6 05 50 f4 05 01 01 e8 60 e5 4f 00 <0f> 0b c3 cc cc cc cc 80 3d 3b f4 05 01 00 0f 85 5e ff ff ff 48 c7
> [ 338.005245] RSP: 0018:ffffa36802e4bd50 EFLAGS: 00010282
> [ 338.006621] RAX: 0000000000000000 RBX: 0000000000000008 RCX: 0000000000000000
> [ 338.008273] RDX: 0000000000000001 RSI: ffffffff9de03ef5 RDI: 00000000ffffffff
> [ 338.009804] RBP: 0000000000000003 R08: 0000000000000000 R09: ffffa36802e4bc00
> [ 338.011719] R10: 0000000000000003 R11: ffffffff9e0bfdc8 R12: ffff9578da461b80
> [ 338.013533] R13: 0000000000000001 R14: ffff9578da422280 R15: ffff9578da461b80
> [ 338.015238] FS: 0000000000000000(0000) GS:ffff957a37d00000(0000) knlGS:0000000000000000
> [ 338.017179] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 338.018680] CR2: 00007f324c1e1c08 CR3: 000000020360a004 CR4: 0000000000060ee0
> [ 338.020377] Call Trace:
> [ 338.021190] <TASK>
> [ 338.021956] release_all_access+0x96/0x120 [nfsd]
> [ 338.023192] ? _raw_spin_unlock+0x15/0x30
> [ 338.024192] nfsd4_close+0x275/0x3d0 [nfsd]
> [ 338.025468] ? fh_verify+0x45e/0x780 [nfsd]
> [ 338.027535] ? __pfx_nfsd4_encode_noop+0x10/0x10 [nfsd]
> [ 338.028775] ? nfsd4_encode_operation+0xae/0x280 [nfsd]
> [ 338.030593] nfsd4_proc_compound+0x3ae/0x6f0 [nfsd]
> [ 338.032341] nfsd_dispatch+0x16a/0x270 [nfsd]
> [ 338.034667] svc_process_common+0x2eb/0x660 [sunrpc]
> [ 338.036614] ? __pfx_nfsd_dispatch+0x10/0x10 [nfsd]
> [ 338.038827] ? __pfx_nfsd+0x10/0x10 [nfsd]
> [ 338.040267] svc_process+0xad/0x100 [sunrpc]
> [ 338.041981] nfsd+0xd5/0x190 [nfsd]
> [ 338.043362] kthread+0xe9/0x110
> [ 338.044680] ? __pfx_kthread+0x10/0x10
> [ 338.046376] ret_from_fork+0x2c/0x50
> [ 338.047892] </TASK>
> [ 338.049067] ---[ end trace 0000000000000000 ]---
> [ 760.792789] BUG: kernel NULL pointer dereference, address: 0000000000000078
> [ 760.795933] #PF: supervisor read access in kernel mode
> [ 760.797477] #PF: error_code(0x0000) - not-present page
> [ 760.799120] PGD 0 P4D 0
> [ 760.800140] Oops: 0000 [#1] PREEMPT SMP PTI
> [ 760.801383] CPU: 2 PID: 3401 Comm: nfsd Tainted: G W E 6.2.0-rc3+ #11
> [ 760.803120] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.1-2.fc37 04/01/2014
> [ 760.805018] RIP: 0010:filp_close+0x23/0x70
> [ 760.806099] Code: 90 90 90 90 90 90 90 0f 1f 44 00 00 41 54 55 53 48 8b 47 38 48 85 c0 0f 84 41 e1 6d 00 48 8b 47 28 48 89 fb 48 89 f5 45 31 e4 <48> 8b 40 78 48 85 c0 74 08 e8 6f 70 72 00 41 89 c4 f6 43 45 40 75
> [ 760.809737] RSP: 0018:ffffa36802e4bc78 EFLAGS: 00010246
> [ 760.811084] RAX: 0000000000000000 RBX: ffff9578c7d4d600 RCX: 0000000000000000
> [ 760.812540] RDX: 000000000000098d RSI: 0000000000000000 RDI: ffff9578c7d4d600
> [ 760.814433] RBP: 0000000000000000 R08: 0000011335048e60 R09: ffff9578f82f1540
> [ 760.816089] R10: ffffa36802e4bcd0 R11: ffffa36802e4bcd8 R12: 0000000000000000
> [ 760.817529] R13: 0000000000000001 R14: dead000000000100 R15: ffff9578f82f1558
> [ 760.818982] FS: 0000000000000000(0000) GS:ffff957a37c80000(0000) knlGS:0000000000000000
> [ 760.820544] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 760.821734] CR2: 0000000000000078 CR3: 00000001565ce002 CR4: 0000000000060ee0
> [ 760.823141] Call Trace:
> [ 760.823808] <TASK>
> [ 760.824419] nfsd_file_free+0xe9/0x210 [nfsd]
> [ 760.825610] release_all_access+0x96/0x120 [nfsd]
> [ 760.826680] nfs4_free_ol_stateid+0x22/0x60 [nfsd]
> [ 760.827747] free_ol_stateid_reaplist+0x61/0x90 [nfsd]
> [ 760.828858] release_openowner+0x258/0x2a0 [nfsd]
> [ 760.829792] __destroy_client+0x183/0x290 [nfsd]
> [ 760.830694] nfsd4_setclientid_confirm+0x1a3/0x4f0 [nfsd]
> [ 760.831763] nfsd4_proc_compound+0x3ae/0x6f0 [nfsd]
> [ 760.832717] nfsd_dispatch+0x16a/0x270 [nfsd]
> [ 760.833576] svc_process_common+0x2eb/0x660 [sunrpc]
> [ 760.834587] ? __pfx_nfsd_dispatch+0x10/0x10 [nfsd]
> [ 760.835576] ? __pfx_nfsd+0x10/0x10 [nfsd]
> [ 760.836462] svc_process+0xad/0x100 [sunrpc]
> [ 760.837317] nfsd+0xd5/0x190 [nfsd]
> [ 760.838133] kthread+0xe9/0x110
> [ 760.838862] ? __pfx_kthread+0x10/0x10
> [ 760.839755] ret_from_fork+0x2c/0x50
> [ 760.840534] </TASK>
> [ 760.841167] Modules linked in: nfsd(E) auth_rpcgss(E) nfs_acl(E) lockd(E) grace(E) sunrpc(E) nls_iso8859_1(E) nls_cp437(E) vfat(E) fat(E) ext4(E) crc16(E) cirrus(E) kvm_intel(E) 9p(E) mbcache(E) joydev(E) virtio_net(E) drm_shmem_helper(E) net_failover(E) kvm(E) jbd2(E) netfs(E) psmouse(E) evdev(E) pcspkr(E) failover(E) irqbypass(E) virtio_balloon(E) drm_kms_helper(E) 9pnet_virtio(E) button(E) drm(E) configfs(E) zram(E) zsmalloc(E) crct10dif_pclmul(E) crc32_pclmul(E) nvme(E) ghash_clmulni_intel(E) virtio_blk(E) sha512_ssse3(E) sha512_generic(E) nvme_core(E) t10_pi(E) virtio_pci(E) virtio(E) crc64_rocksoft_generic(E) aesni_intel(E) crypto_simd(E) crc64_rocksoft(E) virtio_pci_legacy_dev(E) i6300esb(E) cryptd(E) serio_raw(E) crc64(E) virtio_pci_modern_dev(E) virtio_ring(E) btrfs(E) blake2b_generic(E) xor(E) raid6_pq(E) libcrc32c(E) crc32c_generic(E) crc32c_intel(E) autofs4(E)
> [ 760.853527] CR2: 0000000000000078
> [ 760.854340] ---[ end trace 0000000000000000 ]---
> [ 760.855261] RIP: 0010:filp_close+0x23/0x70
> [ 760.856185] Code: 90 90 90 90 90 90 90 0f 1f 44 00 00 41 54 55 53 48 8b 47 38 48 85 c0 0f 84 41 e1 6d 00 48 8b 47 28 48 89 fb 48 89 f5 45 31 e4 <48> 8b 40 78 48 85 c0 74 08 e8 6f 70 72 00 41 89 c4 f6 43 45 40 75
> [ 760.859350] RSP: 0018:ffffa36802e4bc78 EFLAGS: 00010246
> [ 760.860356] RAX: 0000000000000000 RBX: ffff9578c7d4d600 RCX: 0000000000000000
> [ 760.861628] RDX: 000000000000098d RSI: 0000000000000000 RDI: ffff9578c7d4d600
> [ 760.862898] RBP: 0000000000000000 R08: 0000011335048e60 R09: ffff9578f82f1540
> [ 760.864172] R10: ffffa36802e4bcd0 R11: ffffa36802e4bcd8 R12: 0000000000000000
> [ 760.865438] R13: 0000000000000001 R14: dead000000000100 R15: ffff9578f82f1558
> [ 760.866692] FS: 0000000000000000(0000) GS:ffff957a37c80000(0000) knlGS:0000000000000000
> [ 760.868053] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 760.869102] CR2: 0000000000000078 CR3: 00000001565ce002 CR4: 0000000000060ee0
>
> diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
> index 66449c41b19c..b9100707d347 100644
> --- a/fs/nfsd/filecache.c
> +++ b/fs/nfsd/filecache.c
> @@ -908,9 +908,24 @@ __nfsd_file_cache_purge(struct net *net)
> nf = rhashtable_walk_next(&iter);
> while (!IS_ERR_OR_NULL(nf)) {
> if (!net || nf->nf_net == net) {
> - nfsd_file_unhash(nf);
> - nfsd_file_lru_remove(nf);
> - list_add(&nf->nf_lru, &dispose);
> + /* Ignore it if it's no longer hashed */
> + if (!nfsd_file_unhash(nf))
> + continue;
> +
> + /*
> + * Try to claim the LRU ref (if any). If it's
> + * not on the LRU, then try to take a ref. If that
> + * fails, then we'll ignore it.
> + */
> + if (!nfsd_file_lru_remove(nf))
> + nf = nfsd_file_get(nf);
> +
Now that I've looked over this again today, I think this patch is not
quite right. We don't want to try to dequeue it from the lru until we
hold a reference, or we could corrupt the list_head for private users.
I think we want to do the same thing we do when we get a notifier pop in
this case. I'm working on a v2 now and will send it once I've tested it.
Cheers,
> + /*
> + * Now try to put the ref we hold. If that works
> + * and it goes to zero, queue it to be freed.
> + */
> + if (nf && refcount_dec_and_test(&nf->nf_ref))
> + list_add(&nf->nf_lru, &dispose);
> }
> nf = rhashtable_walk_next(&iter);
> }
--
Jeff Layton <[email protected]>
> On Jan 19, 2023, at 2:20 PM, Jeff Layton <[email protected]> wrote:
>
> nfsd_file_cache_purge is called when the server is shutting down, in
> which case, tearing things down is generally fine, but it also gets
> called when the exports cache is flushed.
>
> Instead of walking the cache and freeing everything unconditionally,
> attempt to unhash each entry and get a reference to it, and then put
> that reference. Only queue it to the dispose list if the refcount goes
> to 0.
>
> Fixes: ac3a2585f018 ("nfsd: rework refcounting in filecache")
> Reported-by: Ruben Vestergaard <[email protected]>
> Reported-by: Torkil Svensgaard <[email protected]>
> Reported-by: Shachar Kagan <[email protected]>
> Signed-off-by: Jeffrey Layton <[email protected]>
FYI, checkpatch complained that the Signed-off-by does not
exactly match the From: address. I haven't see "Jeffrey"
before, but the DKIM check passed, so....
.... I've applied this to nfsd-fixes (formerly for-rc).
> ---
> fs/nfsd/filecache.c | 21 ++++++++++++++++++---
> 1 file changed, 18 insertions(+), 3 deletions(-)
>
> I was able to reproduce this today by running pynfs against the server
> while running "exportfs -ra" in a loop. This one is a bit different in
> that it happened in the open codepath, but that's probably just because
> delegations are more likely to be long-lived. With this patch, the
> server survives the run:
>
> [ 337.962027] ------------[ cut here ]------------
> [ 337.963823] refcount_t: underflow; use-after-free.
> [ 337.965502] WARNING: CPU: 6 PID: 3401 at lib/refcount.c:28 refcount_warn_saturate+0xba/0x110
> [ 337.967999] Modules linked in: nfsd(E) auth_rpcgss(E) nfs_acl(E) lockd(E) grace(E) sunrpc(E) nls_iso8859_1(E) nls_cp437(E) vfat(E) fat(E) ext4(E) crc16(E) cirrus(E) kvm_intel(E) 9p(E) mbcache(E) joydev(E) virtio_net(E) drm_shmem_helper(E) net_failover(E) kvm(E) jbd2(E) netfs(E) psmouse(E) evdev(E) pcspkr(E) failover(E) irqbypass(E) virtio_balloon(E) drm_kms_helper(E) 9pnet_virtio(E) button(E) drm(E) configfs(E) zram(E) zsmalloc(E) crct10dif_pclmul(E) crc32_pclmul(E) nvme(E) ghash_clmulni_intel(E) virtio_blk(E) sha512_ssse3(E) sha512_generic(E) nvme_core(E) t10_pi(E) virtio_pci(E) virtio(E) crc64_rocksoft_generic(E) aesni_intel(E) crypto_simd(E) crc64_rocksoft(E) virtio_pci_legacy_dev(E) i6300esb(E) cryptd(E) serio_raw(E) crc64(E) virtio_pci_modern_dev(E) virtio_ring(E) btrfs(E) blake2b_generic(E) xor(E) raid6_pq(E) libcrc32c(E) crc32c_generic(E) crc32c_intel(E) autofs4(E)
> [ 337.992040] CPU: 6 PID: 3401 Comm: nfsd Tainted: G E 6.2.0-rc3+ #11
> [ 337.994701] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.1-2.fc37 04/01/2014
> [ 337.998046] RIP: 0010:refcount_warn_saturate+0xba/0x110
> [ 337.999852] Code: 01 01 e8 83 e5 4f 00 0f 0b c3 cc cc cc cc 80 3d 60 f4 05 01 00 75 85 48 c7 c7 30 b5 e1 9d c6 05 50 f4 05 01 01 e8 60 e5 4f 00 <0f> 0b c3 cc cc cc cc 80 3d 3b f4 05 01 00 0f 85 5e ff ff ff 48 c7
> [ 338.005245] RSP: 0018:ffffa36802e4bd50 EFLAGS: 00010282
> [ 338.006621] RAX: 0000000000000000 RBX: 0000000000000008 RCX: 0000000000000000
> [ 338.008273] RDX: 0000000000000001 RSI: ffffffff9de03ef5 RDI: 00000000ffffffff
> [ 338.009804] RBP: 0000000000000003 R08: 0000000000000000 R09: ffffa36802e4bc00
> [ 338.011719] R10: 0000000000000003 R11: ffffffff9e0bfdc8 R12: ffff9578da461b80
> [ 338.013533] R13: 0000000000000001 R14: ffff9578da422280 R15: ffff9578da461b80
> [ 338.015238] FS: 0000000000000000(0000) GS:ffff957a37d00000(0000) knlGS:0000000000000000
> [ 338.017179] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 338.018680] CR2: 00007f324c1e1c08 CR3: 000000020360a004 CR4: 0000000000060ee0
> [ 338.020377] Call Trace:
> [ 338.021190] <TASK>
> [ 338.021956] release_all_access+0x96/0x120 [nfsd]
> [ 338.023192] ? _raw_spin_unlock+0x15/0x30
> [ 338.024192] nfsd4_close+0x275/0x3d0 [nfsd]
> [ 338.025468] ? fh_verify+0x45e/0x780 [nfsd]
> [ 338.027535] ? __pfx_nfsd4_encode_noop+0x10/0x10 [nfsd]
> [ 338.028775] ? nfsd4_encode_operation+0xae/0x280 [nfsd]
> [ 338.030593] nfsd4_proc_compound+0x3ae/0x6f0 [nfsd]
> [ 338.032341] nfsd_dispatch+0x16a/0x270 [nfsd]
> [ 338.034667] svc_process_common+0x2eb/0x660 [sunrpc]
> [ 338.036614] ? __pfx_nfsd_dispatch+0x10/0x10 [nfsd]
> [ 338.038827] ? __pfx_nfsd+0x10/0x10 [nfsd]
> [ 338.040267] svc_process+0xad/0x100 [sunrpc]
> [ 338.041981] nfsd+0xd5/0x190 [nfsd]
> [ 338.043362] kthread+0xe9/0x110
> [ 338.044680] ? __pfx_kthread+0x10/0x10
> [ 338.046376] ret_from_fork+0x2c/0x50
> [ 338.047892] </TASK>
> [ 338.049067] ---[ end trace 0000000000000000 ]---
> [ 760.792789] BUG: kernel NULL pointer dereference, address: 0000000000000078
> [ 760.795933] #PF: supervisor read access in kernel mode
> [ 760.797477] #PF: error_code(0x0000) - not-present page
> [ 760.799120] PGD 0 P4D 0
> [ 760.800140] Oops: 0000 [#1] PREEMPT SMP PTI
> [ 760.801383] CPU: 2 PID: 3401 Comm: nfsd Tainted: G W E 6.2.0-rc3+ #11
> [ 760.803120] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.1-2.fc37 04/01/2014
> [ 760.805018] RIP: 0010:filp_close+0x23/0x70
> [ 760.806099] Code: 90 90 90 90 90 90 90 0f 1f 44 00 00 41 54 55 53 48 8b 47 38 48 85 c0 0f 84 41 e1 6d 00 48 8b 47 28 48 89 fb 48 89 f5 45 31 e4 <48> 8b 40 78 48 85 c0 74 08 e8 6f 70 72 00 41 89 c4 f6 43 45 40 75
> [ 760.809737] RSP: 0018:ffffa36802e4bc78 EFLAGS: 00010246
> [ 760.811084] RAX: 0000000000000000 RBX: ffff9578c7d4d600 RCX: 0000000000000000
> [ 760.812540] RDX: 000000000000098d RSI: 0000000000000000 RDI: ffff9578c7d4d600
> [ 760.814433] RBP: 0000000000000000 R08: 0000011335048e60 R09: ffff9578f82f1540
> [ 760.816089] R10: ffffa36802e4bcd0 R11: ffffa36802e4bcd8 R12: 0000000000000000
> [ 760.817529] R13: 0000000000000001 R14: dead000000000100 R15: ffff9578f82f1558
> [ 760.818982] FS: 0000000000000000(0000) GS:ffff957a37c80000(0000) knlGS:0000000000000000
> [ 760.820544] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 760.821734] CR2: 0000000000000078 CR3: 00000001565ce002 CR4: 0000000000060ee0
> [ 760.823141] Call Trace:
> [ 760.823808] <TASK>
> [ 760.824419] nfsd_file_free+0xe9/0x210 [nfsd]
> [ 760.825610] release_all_access+0x96/0x120 [nfsd]
> [ 760.826680] nfs4_free_ol_stateid+0x22/0x60 [nfsd]
> [ 760.827747] free_ol_stateid_reaplist+0x61/0x90 [nfsd]
> [ 760.828858] release_openowner+0x258/0x2a0 [nfsd]
> [ 760.829792] __destroy_client+0x183/0x290 [nfsd]
> [ 760.830694] nfsd4_setclientid_confirm+0x1a3/0x4f0 [nfsd]
> [ 760.831763] nfsd4_proc_compound+0x3ae/0x6f0 [nfsd]
> [ 760.832717] nfsd_dispatch+0x16a/0x270 [nfsd]
> [ 760.833576] svc_process_common+0x2eb/0x660 [sunrpc]
> [ 760.834587] ? __pfx_nfsd_dispatch+0x10/0x10 [nfsd]
> [ 760.835576] ? __pfx_nfsd+0x10/0x10 [nfsd]
> [ 760.836462] svc_process+0xad/0x100 [sunrpc]
> [ 760.837317] nfsd+0xd5/0x190 [nfsd]
> [ 760.838133] kthread+0xe9/0x110
> [ 760.838862] ? __pfx_kthread+0x10/0x10
> [ 760.839755] ret_from_fork+0x2c/0x50
> [ 760.840534] </TASK>
> [ 760.841167] Modules linked in: nfsd(E) auth_rpcgss(E) nfs_acl(E) lockd(E) grace(E) sunrpc(E) nls_iso8859_1(E) nls_cp437(E) vfat(E) fat(E) ext4(E) crc16(E) cirrus(E) kvm_intel(E) 9p(E) mbcache(E) joydev(E) virtio_net(E) drm_shmem_helper(E) net_failover(E) kvm(E) jbd2(E) netfs(E) psmouse(E) evdev(E) pcspkr(E) failover(E) irqbypass(E) virtio_balloon(E) drm_kms_helper(E) 9pnet_virtio(E) button(E) drm(E) configfs(E) zram(E) zsmalloc(E) crct10dif_pclmul(E) crc32_pclmul(E) nvme(E) ghash_clmulni_intel(E) virtio_blk(E) sha512_ssse3(E) sha512_generic(E) nvme_core(E) t10_pi(E) virtio_pci(E) virtio(E) crc64_rocksoft_generic(E) aesni_intel(E) crypto_simd(E) crc64_rocksoft(E) virtio_pci_legacy_dev(E) i6300esb(E) cryptd(E) serio_raw(E) crc64(E) virtio_pci_modern_dev(E) virtio_ring(E) btrfs(E) blake2b_generic(E) xor(E) raid6_pq(E) libcrc32c(E) crc32c_generic(E) crc32c_intel(E) autofs4(E)
> [ 760.853527] CR2: 0000000000000078
> [ 760.854340] ---[ end trace 0000000000000000 ]---
> [ 760.855261] RIP: 0010:filp_close+0x23/0x70
> [ 760.856185] Code: 90 90 90 90 90 90 90 0f 1f 44 00 00 41 54 55 53 48 8b 47 38 48 85 c0 0f 84 41 e1 6d 00 48 8b 47 28 48 89 fb 48 89 f5 45 31 e4 <48> 8b 40 78 48 85 c0 74 08 e8 6f 70 72 00 41 89 c4 f6 43 45 40 75
> [ 760.859350] RSP: 0018:ffffa36802e4bc78 EFLAGS: 00010246
> [ 760.860356] RAX: 0000000000000000 RBX: ffff9578c7d4d600 RCX: 0000000000000000
> [ 760.861628] RDX: 000000000000098d RSI: 0000000000000000 RDI: ffff9578c7d4d600
> [ 760.862898] RBP: 0000000000000000 R08: 0000011335048e60 R09: ffff9578f82f1540
> [ 760.864172] R10: ffffa36802e4bcd0 R11: ffffa36802e4bcd8 R12: 0000000000000000
> [ 760.865438] R13: 0000000000000001 R14: dead000000000100 R15: ffff9578f82f1558
> [ 760.866692] FS: 0000000000000000(0000) GS:ffff957a37c80000(0000) knlGS:0000000000000000
> [ 760.868053] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 760.869102] CR2: 0000000000000078 CR3: 00000001565ce002 CR4: 0000000000060ee0
>
> diff --git a/fs/nfsd/filecache.c b/fs/nfsd/filecache.c
> index 66449c41b19c..b9100707d347 100644
> --- a/fs/nfsd/filecache.c
> +++ b/fs/nfsd/filecache.c
> @@ -908,9 +908,24 @@ __nfsd_file_cache_purge(struct net *net)
> nf = rhashtable_walk_next(&iter);
> while (!IS_ERR_OR_NULL(nf)) {
> if (!net || nf->nf_net == net) {
> - nfsd_file_unhash(nf);
> - nfsd_file_lru_remove(nf);
> - list_add(&nf->nf_lru, &dispose);
> + /* Ignore it if it's no longer hashed */
> + if (!nfsd_file_unhash(nf))
> + continue;
> +
> + /*
> + * Try to claim the LRU ref (if any). If it's
> + * not on the LRU, then try to take a ref. If that
> + * fails, then we'll ignore it.
> + */
> + if (!nfsd_file_lru_remove(nf))
> + nf = nfsd_file_get(nf);
> +
> + /*
> + * Now try to put the ref we hold. If that works
> + * and it goes to zero, queue it to be freed.
> + */
> + if (nf && refcount_dec_and_test(&nf->nf_ref))
> + list_add(&nf->nf_lru, &dispose);
> }
> nf = rhashtable_walk_next(&iter);
> }
> --
> 2.39.0
>
--
Chuck Lever