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nfs_common: must not hold RCU while calling nfsd_file_put_local

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Move holding the RCU from nfs_to_nfsd_file_put_local to
nfs_to_nfsd_net_put.  It is the call to nfs_to->nfsd_serv_put that
requires the RCU anyway (the puts for nfsd_file and netns were
combined to avoid an extra indirect reference but that
micro-optimization isn't possible now).

This fixes xfstests generic/013 and it triggering:

"Voluntary context switch within RCU read-side critical section!"

[  143.545738] Call Trace:
[  143.546206]  <TASK>
[  143.546625]  ? show_regs+0x6d/0x80
[  143.547267]  ? __warn+0x91/0x140
[  143.547951]  ? rcu_note_context_switch+0x496/0x5d0
[  143.548856]  ? report_bug+0x193/0x1a0
[  143.549557]  ? handle_bug+0x63/0xa0
[  143.550214]  ? exc_invalid_op+0x1d/0x80
[  143.550938]  ? asm_exc_invalid_op+0x1f/0x30
[  143.551736]  ? rcu_note_context_switch+0x496/0x5d0
[  143.552634]  ? wakeup_preempt+0x62/0x70
[  143.553358]  __schedule+0xaa/0x1380
[  143.554025]  ? _raw_spin_unlock_irqrestore+0x12/0x40
[  143.554958]  ? try_to_wake_up+0x1fe/0x6b0
[  143.555715]  ? wake_up_process+0x19/0x20
[  143.556452]  schedule+0x2e/0x120
[  143.557066]  schedule_preempt_disabled+0x19/0x30
[  143.557933]  rwsem_down_read_slowpath+0x24d/0x4a0
[  143.558818]  ? xfs_efi_item_format+0x50/0xc0 [xfs]
[  143.559894]  down_read+0x4e/0xb0
[  143.560519]  xlog_cil_commit+0x1b2/0xbc0 [xfs]
[  143.561460]  ? _raw_spin_unlock+0x12/0x30
[  143.562212]  ? xfs_inode_item_precommit+0xc7/0x220 [xfs]
[  143.563309]  ? xfs_trans_run_precommits+0x69/0xd0 [xfs]
[  143.564394]  __xfs_trans_commit+0xb5/0x330 [xfs]
[  143.565367]  xfs_trans_roll+0x48/0xc0 [xfs]
[  143.566262]  xfs_defer_trans_roll+0x57/0x100 [xfs]
[  143.567278]  xfs_defer_finish_noroll+0x27a/0x490 [xfs]
[  143.568342]  xfs_defer_finish+0x1a/0x80 [xfs]
[  143.569267]  xfs_bunmapi_range+0x4d/0xb0 [xfs]
[  143.570208]  xfs_itruncate_extents_flags+0x13d/0x230 [xfs]
[  143.571353]  xfs_free_eofblocks+0x12e/0x190 [xfs]
[  143.572359]  xfs_file_release+0x12d/0x140 [xfs]
[  143.573324]  __fput+0xe8/0x2d0
[  143.573922]  __fput_sync+0x1d/0x30
[  143.574574]  nfsd_filp_close+0x33/0x60 [nfsd]
[  143.575430]  nfsd_file_free+0x96/0x150 [nfsd]
[  143.576274]  nfsd_file_put+0xf7/0x1a0 [nfsd]
[  143.577104]  nfsd_file_put_local+0x18/0x30 [nfsd]
[  143.578070]  nfs_close_local_fh+0x101/0x110 [nfs_localio]
[  143.579079]  __put_nfs_open_context+0xc9/0x180 [nfs]
[  143.580031]  nfs_file_clear_open_context+0x4a/0x60 [nfs]
[  143.581038]  nfs_file_release+0x3e/0x60 [nfs]
[  143.581879]  __fput+0xe8/0x2d0
[  143.582464]  __fput_sync+0x1d/0x30
[  143.583108]  __x64_sys_close+0x41/0x80
[  143.583823]  x64_sys_call+0x189a/0x20d0
[  143.584552]  do_syscall_64+0x64/0x170
[  143.585240]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[  143.586185] RIP: 0033:0x7f3c5153efd7

Fixes: 65f2a5c366 ("nfs_common: fix race in NFS calls to nfsd_file_put_local() and nfsd_serv_put()")
Signed-off-by: Mike Snitzer <snitzer@kernel.org>
Reviewed-by: NeilBrown <neilb@suse.de>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
This commit is contained in:
Mike Snitzer 2024-11-13 22:59:38 -05:00 committed by Chuck Lever
parent 07442ec85b
commit c840b8e1f0
4 changed files with 26 additions and 16 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
fs/nfs_common/nfslocalio.c
View File

@ -155,11 +155,9 @@ struct nfsd_file *nfs_open_local_fh(nfs_uuid_t *uuid,
/* We have an implied reference to net thanks to nfsd_serv_try_get */ /* We have an implied reference to net thanks to nfsd_serv_try_get */
localio = nfs_to->nfsd_open_local_fh(net, uuid->dom, rpc_clnt, localio = nfs_to->nfsd_open_local_fh(net, uuid->dom, rpc_clnt,
cred, nfs_fh, fmode); cred, nfs_fh, fmode);
if (IS_ERR(localio)) { if (IS_ERR(localio))
rcu_read_lock(); nfs_to_nfsd_net_put(net);
nfs_to->nfsd_serv_put(net);
rcu_read_unlock();
}
return localio; return localio;
} }
EXPORT_SYMBOL_GPL(nfs_open_local_fh); EXPORT_SYMBOL_GPL(nfs_open_local_fh);

14
fs/nfsd/filecache.c
View File

@ -391,19 +391,19 @@ nfsd_file_put(struct nfsd_file *nf)
} }
/** /**
* nfsd_file_put_local - put the reference to nfsd_file and local nfsd_serv * nfsd_file_put_local - put nfsd_file reference and arm nfsd_serv_put in caller
* @nf: nfsd_file of which to put the references * @nf: nfsd_file of which to put the reference
* *
* First put the reference of the nfsd_file and then put the * First save the associated net to return to caller, then put
* reference to the associated nn->nfsd_serv. * the reference of the nfsd_file.
*/ */
void struct net *
nfsd_file_put_local(struct nfsd_file *nf) __must_hold(rcu) nfsd_file_put_local(struct nfsd_file *nf)
{ {
struct net *net = nf->nf_net; struct net *net = nf->nf_net;
nfsd_file_put(nf); nfsd_file_put(nf);
nfsd_serv_put(net); return net;
} }
/** /**

2
fs/nfsd/filecache.h
View File

@ -55,7 +55,7 @@ void nfsd_file_cache_shutdown(void);
int nfsd_file_cache_start_net(struct net *net); int nfsd_file_cache_start_net(struct net *net);
void nfsd_file_cache_shutdown_net(struct net *net); void nfsd_file_cache_shutdown_net(struct net *net);
void nfsd_file_put(struct nfsd_file *nf); void nfsd_file_put(struct nfsd_file *nf);
void nfsd_file_put_local(struct nfsd_file *nf); struct net *nfsd_file_put_local(struct nfsd_file *nf);
struct nfsd_file *nfsd_file_get(struct nfsd_file *nf); struct nfsd_file *nfsd_file_get(struct nfsd_file *nf);
struct file *nfsd_file_file(struct nfsd_file *nf); struct file *nfsd_file_file(struct nfsd_file *nf);
void nfsd_file_close_inode_sync(struct inode *inode); void nfsd_file_close_inode_sync(struct inode *inode);

18
include/linux/nfslocalio.h
View File

@ -55,7 +55,7 @@ struct nfsd_localio_operations {
const struct cred *, const struct cred *,
const struct nfs_fh *, const struct nfs_fh *,
const fmode_t); const fmode_t);
void (*nfsd_file_put_local)(struct nfsd_file *); struct net *(*nfsd_file_put_local)(struct nfsd_file *);
struct file *(*nfsd_file_file)(struct nfsd_file *); struct file *(*nfsd_file_file)(struct nfsd_file *);
} ____cacheline_aligned; } ____cacheline_aligned;
@ -66,7 +66,7 @@ struct nfsd_file *nfs_open_local_fh(nfs_uuid_t *,
struct rpc_clnt *, const struct cred *, struct rpc_clnt *, const struct cred *,
const struct nfs_fh *, const fmode_t); const struct nfs_fh *, const fmode_t);
static inline void nfs_to_nfsd_file_put_local(struct nfsd_file *localio) static inline void nfs_to_nfsd_net_put(struct net *net)
{ {
/* /*
* Once reference to nfsd_serv is dropped, NFSD could be * Once reference to nfsd_serv is dropped, NFSD could be
@ -74,10 +74,22 @@ static inline void nfs_to_nfsd_file_put_local(struct nfsd_file *localio)
* by always taking RCU. * by always taking RCU.
*/ */
rcu_read_lock(); rcu_read_lock();
nfs_to->nfsd_file_put_local(localio); nfs_to->nfsd_serv_put(net);
rcu_read_unlock(); rcu_read_unlock();
} }
static inline void nfs_to_nfsd_file_put_local(struct nfsd_file *localio)
{
/*
* Must not hold RCU otherwise nfsd_file_put() can easily trigger:
* "Voluntary context switch within RCU read-side critical section!"
* by scheduling deep in underlying filesystem (e.g. XFS).
*/
struct net *net = nfs_to->nfsd_file_put_local(localio);
nfs_to_nfsd_net_put(net);
}
#else /* CONFIG_NFS_LOCALIO */ #else /* CONFIG_NFS_LOCALIO */
static inline void nfsd_localio_ops_init(void) static inline void nfsd_localio_ops_init(void)
{ {