From: "J. Bruce Fields" bfields@redhat.com
[ Upstream commit 027690c75e8fd91b60a634d31c4891a6e39d45bd ]
I made every global per-network-namespace instead. But perhaps doing that to this slab was a step too far.
The kmem_cache_create call in our net init method also seems to be responsible for this lockdep warning:
[ 45.163710] Unable to find swap-space signature [ 45.375718] trinity-c1 (855): attempted to duplicate a private mapping with mremap. This is not supported. [ 46.055744] futex_wake_op: trinity-c1 tries to shift op by -209; fix this program [ 51.011723] [ 51.013378] ====================================================== [ 51.013875] WARNING: possible circular locking dependency detected [ 51.014378] 5.2.0-rc2 #1 Not tainted [ 51.014672] ------------------------------------------------------ [ 51.015182] trinity-c2/886 is trying to acquire lock: [ 51.015593] 000000005405f099 (slab_mutex){+.+.}, at: slab_attr_store+0xa2/0x130 [ 51.016190] [ 51.016190] but task is already holding lock: [ 51.016652] 00000000ac662005 (kn->count#43){++++}, at: kernfs_fop_write+0x286/0x500 [ 51.017266] [ 51.017266] which lock already depends on the new lock. [ 51.017266] [ 51.017909] [ 51.017909] the existing dependency chain (in reverse order) is: [ 51.018497] [ 51.018497] -> #1 (kn->count#43){++++}: [ 51.018956] __lock_acquire+0x7cf/0x1a20 [ 51.019317] lock_acquire+0x17d/0x390 [ 51.019658] __kernfs_remove+0x892/0xae0 [ 51.020020] kernfs_remove_by_name_ns+0x78/0x110 [ 51.020435] sysfs_remove_link+0x55/0xb0 [ 51.020832] sysfs_slab_add+0xc1/0x3e0 [ 51.021332] __kmem_cache_create+0x155/0x200 [ 51.021720] create_cache+0xf5/0x320 [ 51.022054] kmem_cache_create_usercopy+0x179/0x320 [ 51.022486] kmem_cache_create+0x1a/0x30 [ 51.022867] nfsd_reply_cache_init+0x278/0x560 [ 51.023266] nfsd_init_net+0x20f/0x5e0 [ 51.023623] ops_init+0xcb/0x4b0 [ 51.023928] setup_net+0x2fe/0x670 [ 51.024315] copy_net_ns+0x30a/0x3f0 [ 51.024653] create_new_namespaces+0x3c5/0x820 [ 51.025257] unshare_nsproxy_namespaces+0xd1/0x240 [ 51.025881] ksys_unshare+0x506/0x9c0 [ 51.026381] __x64_sys_unshare+0x3a/0x50 [ 51.026937] do_syscall_64+0x110/0x10b0 [ 51.027509] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 51.028175] [ 51.028175] -> #0 (slab_mutex){+.+.}: [ 51.028817] validate_chain+0x1c51/0x2cc0 [ 51.029422] __lock_acquire+0x7cf/0x1a20 [ 51.029947] lock_acquire+0x17d/0x390 [ 51.030438] __mutex_lock+0x100/0xfa0 [ 51.030995] mutex_lock_nested+0x27/0x30 [ 51.031516] slab_attr_store+0xa2/0x130 [ 51.032020] sysfs_kf_write+0x11d/0x180 [ 51.032529] kernfs_fop_write+0x32a/0x500 [ 51.033056] do_loop_readv_writev+0x21d/0x310 [ 51.033627] do_iter_write+0x2e5/0x380 [ 51.034148] vfs_writev+0x170/0x310 [ 51.034616] do_pwritev+0x13e/0x160 [ 51.035100] __x64_sys_pwritev+0xa3/0x110 [ 51.035633] do_syscall_64+0x110/0x10b0 [ 51.036200] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 51.036924] [ 51.036924] other info that might help us debug this: [ 51.036924] [ 51.037876] Possible unsafe locking scenario: [ 51.037876] [ 51.038556] CPU0 CPU1 [ 51.039130] ---- ---- [ 51.039676] lock(kn->count#43); [ 51.040084] lock(slab_mutex); [ 51.040597] lock(kn->count#43); [ 51.041062] lock(slab_mutex); [ 51.041320] [ 51.041320] *** DEADLOCK *** [ 51.041320] [ 51.041793] 3 locks held by trinity-c2/886: [ 51.042128] #0: 000000001f55e152 (sb_writers#5){.+.+}, at: vfs_writev+0x2b9/0x310 [ 51.042739] #1: 00000000c7d6c034 (&of->mutex){+.+.}, at: kernfs_fop_write+0x25b/0x500 [ 51.043400] #2: 00000000ac662005 (kn->count#43){++++}, at: kernfs_fop_write+0x286/0x500
Reported-by: kernel test robot lkp@intel.com Fixes: 3ba75830ce17 "drc containerization" Signed-off-by: J. Bruce Fields bfields@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- fs/nfsd/cache.h | 2 ++ fs/nfsd/netns.h | 1 - fs/nfsd/nfscache.c | 29 +++++++++++++++++------------ fs/nfsd/nfsctl.c | 6 ++++++ 4 files changed, 25 insertions(+), 13 deletions(-)
diff --git a/fs/nfsd/cache.h b/fs/nfsd/cache.h index 10ec5ecdf117..65c331f75e9c 100644 --- a/fs/nfsd/cache.h +++ b/fs/nfsd/cache.h @@ -78,6 +78,8 @@ enum { /* Checksum this amount of the request */ #define RC_CSUMLEN (256U)
+int nfsd_drc_slab_create(void); +void nfsd_drc_slab_free(void); int nfsd_reply_cache_init(struct nfsd_net *); void nfsd_reply_cache_shutdown(struct nfsd_net *); int nfsd_cache_lookup(struct svc_rqst *); diff --git a/fs/nfsd/netns.h b/fs/nfsd/netns.h index 09aa545825bd..9217cb64bf0e 100644 --- a/fs/nfsd/netns.h +++ b/fs/nfsd/netns.h @@ -139,7 +139,6 @@ struct nfsd_net { * Duplicate reply cache */ struct nfsd_drc_bucket *drc_hashtbl; - struct kmem_cache *drc_slab;
/* max number of entries allowed in the cache */ unsigned int max_drc_entries; diff --git a/fs/nfsd/nfscache.c b/fs/nfsd/nfscache.c index 96352ab7bd81..0c10bfea039e 100644 --- a/fs/nfsd/nfscache.c +++ b/fs/nfsd/nfscache.c @@ -36,6 +36,8 @@ struct nfsd_drc_bucket { spinlock_t cache_lock; };
+static struct kmem_cache *drc_slab; + static int nfsd_cache_append(struct svc_rqst *rqstp, struct kvec *vec); static unsigned long nfsd_reply_cache_count(struct shrinker *shrink, struct shrink_control *sc); @@ -95,7 +97,7 @@ nfsd_reply_cache_alloc(struct svc_rqst *rqstp, __wsum csum, { struct svc_cacherep *rp;
- rp = kmem_cache_alloc(nn->drc_slab, GFP_KERNEL); + rp = kmem_cache_alloc(drc_slab, GFP_KERNEL); if (rp) { rp->c_state = RC_UNUSED; rp->c_type = RC_NOCACHE; @@ -129,7 +131,7 @@ nfsd_reply_cache_free_locked(struct nfsd_drc_bucket *b, struct svc_cacherep *rp, atomic_dec(&nn->num_drc_entries); nn->drc_mem_usage -= sizeof(*rp); } - kmem_cache_free(nn->drc_slab, rp); + kmem_cache_free(drc_slab, rp); }
static void @@ -141,6 +143,18 @@ nfsd_reply_cache_free(struct nfsd_drc_bucket *b, struct svc_cacherep *rp, spin_unlock(&b->cache_lock); }
+int nfsd_drc_slab_create(void) +{ + drc_slab = kmem_cache_create("nfsd_drc", + sizeof(struct svc_cacherep), 0, 0, NULL); + return drc_slab ? 0: -ENOMEM; +} + +void nfsd_drc_slab_free(void) +{ + kmem_cache_destroy(drc_slab); +} + int nfsd_reply_cache_init(struct nfsd_net *nn) { unsigned int hashsize; @@ -159,18 +173,13 @@ int nfsd_reply_cache_init(struct nfsd_net *nn) if (status) goto out_nomem;
- nn->drc_slab = kmem_cache_create("nfsd_drc", - sizeof(struct svc_cacherep), 0, 0, NULL); - if (!nn->drc_slab) - goto out_shrinker; - nn->drc_hashtbl = kcalloc(hashsize, sizeof(*nn->drc_hashtbl), GFP_KERNEL); if (!nn->drc_hashtbl) { nn->drc_hashtbl = vzalloc(array_size(hashsize, sizeof(*nn->drc_hashtbl))); if (!nn->drc_hashtbl) - goto out_slab; + goto out_shrinker; }
for (i = 0; i < hashsize; i++) { @@ -180,8 +189,6 @@ int nfsd_reply_cache_init(struct nfsd_net *nn) nn->drc_hashsize = hashsize;
return 0; -out_slab: - kmem_cache_destroy(nn->drc_slab); out_shrinker: unregister_shrinker(&nn->nfsd_reply_cache_shrinker); out_nomem: @@ -209,8 +216,6 @@ void nfsd_reply_cache_shutdown(struct nfsd_net *nn) nn->drc_hashtbl = NULL; nn->drc_hashsize = 0;
- kmem_cache_destroy(nn->drc_slab); - nn->drc_slab = NULL; }
/* diff --git a/fs/nfsd/nfsctl.c b/fs/nfsd/nfsctl.c index 3bb2db947d29..71687d99b090 100644 --- a/fs/nfsd/nfsctl.c +++ b/fs/nfsd/nfsctl.c @@ -1533,6 +1533,9 @@ static int __init init_nfsd(void) goto out_free_slabs; nfsd_fault_inject_init(); /* nfsd fault injection controls */ nfsd_stat_init(); /* Statistics */ + retval = nfsd_drc_slab_create(); + if (retval) + goto out_free_stat; nfsd_lockd_init(); /* lockd->nfsd callbacks */ retval = create_proc_exports_entry(); if (retval) @@ -1546,6 +1549,8 @@ static int __init init_nfsd(void) remove_proc_entry("fs/nfs", NULL); out_free_lockd: nfsd_lockd_shutdown(); + nfsd_drc_slab_free(); +out_free_stat: nfsd_stat_shutdown(); nfsd_fault_inject_cleanup(); nfsd4_exit_pnfs(); @@ -1560,6 +1565,7 @@ static int __init init_nfsd(void)
static void __exit exit_nfsd(void) { + nfsd_drc_slab_free(); remove_proc_entry("fs/nfs/exports", NULL); remove_proc_entry("fs/nfs", NULL); nfsd_stat_shutdown();