Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933314AbbLHKrS (ORCPT ); Tue, 8 Dec 2015 05:47:18 -0500 Received: from casper.infradead.org ([85.118.1.10]:45014 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932540AbbLHKrP (ORCPT ); Tue, 8 Dec 2015 05:47:15 -0500 Date: Tue, 8 Dec 2015 11:47:12 +0100 From: Peter Zijlstra To: torvalds@linux-foundation.org, tglx@linutronix.de, linux-kernel@vger.kernel.org, efault@gmx.de, mingo@kernel.org, hpa@zytor.com, vladimir.murzin@arm.com Cc: linux-tip-commits@vger.kernel.org, jstancek@redhat.com, Oleg Nesterov Subject: Re: [tip:locking/core] sched/wait: Fix signal handling in bit wait helpers Message-ID: <20151208104712.GJ6356@twins.programming.kicks-ass.net> References: <20151201130404.GL3816@twins.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2012-12-30) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10692 Lines: 301 On Fri, Dec 04, 2015 at 03:52:12AM -0800, tip-bot for Peter Zijlstra wrote: > Commit-ID: 68985633bccb6066bf1803e316fbc6c1f5b796d6 > Gitweb: http://git.kernel.org/tip/68985633bccb6066bf1803e316fbc6c1f5b796d6 > Author: Peter Zijlstra > AuthorDate: Tue, 1 Dec 2015 14:04:04 +0100 > Committer: Ingo Molnar > CommitDate: Fri, 4 Dec 2015 10:10:15 +0100 > > sched/wait: Fix signal handling in bit wait helpers > > Vladimir reported getting RCU stall warnings and bisected it back to > commit: > > 743162013d40 ("sched: Remove proliferation of wait_on_bit() action functions") > > That commit inadvertently reversed the calls to schedule() and signal_pending(), > thereby not handling the case where the signal receives while we sleep. > > Reported-by: Vladimir Murzin > Tested-by: Vladimir Murzin > Signed-off-by: Peter Zijlstra (Intel) > Cc: Linus Torvalds > Cc: Mike Galbraith > Cc: Peter Zijlstra > Cc: Thomas Gleixner > Cc: mark.rutland@arm.com > Cc: neilb@suse.de > Cc: oleg@redhat.com > Fixes: 743162013d40 ("sched: Remove proliferation of wait_on_bit() action functions") > Fixes: cbbce8220949 ("SCHED: add some "wait..on_bit...timeout()" interfaces.") > Link: http://lkml.kernel.org/r/20151201130404.GL3816@twins.programming.kicks-ass.net > Signed-off-by: Ingo Molnar > --- > kernel/sched/wait.c | 16 ++++++++-------- > 1 file changed, 8 insertions(+), 8 deletions(-) > > diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c > index 052e026..f10bd87 100644 > --- a/kernel/sched/wait.c > +++ b/kernel/sched/wait.c > @@ -583,18 +583,18 @@ EXPORT_SYMBOL(wake_up_atomic_t); > > __sched int bit_wait(struct wait_bit_key *word) > { > - if (signal_pending_state(current->state, current)) > - return 1; > schedule(); > + if (signal_pending(current)) > + return -EINTR; > return 0; > } *sigh*, so that patch was broken.. the below might fix it, but please someone look at it, I seem to have a less than stellar track record here... --- Subject: sched/wait: Fix the signal handling fix Jan Stancek reported that I wrecked things for him by fixing things for Vladimir :/ His report was due to an UNINTERRUPTIBLE wait getting -EINTR, which should not be possible, however my previous patch made this possible by unconditionally checking signal_pending(). We cannot use current->state as was done previously, because the instruction after the store to that variable it can be changed. We must instead pass the initial state along and use that. Fixes: 68985633bccb ("sched/wait: Fix signal handling in bit wait helpers") Cc: Linus Torvalds Cc: Mike Galbraith Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: mark.rutland@arm.com Cc: neilb@suse.de Cc: oleg@redhat.com Cc: Vladimir Murzin Reported-by: Jan Stancek Tested-by: Jan Stancek Signed-off-by: Peter Zijlstra (Intel) --- fs/cifs/inode.c | 6 +++--- fs/nfs/inode.c | 6 +++--- fs/nfs/internal.h | 2 +- fs/nfs/pagelist.c | 2 +- fs/nfs/pnfs.c | 4 ++-- include/linux/wait.h | 10 +++++----- kernel/sched/wait.c | 20 ++++++++++---------- net/sunrpc/sched.c | 6 +++--- 8 files changed, 28 insertions(+), 28 deletions(-) diff --git a/fs/cifs/inode.c b/fs/cifs/inode.c index 6b66dd5..a329f5b 100644 --- a/fs/cifs/inode.c +++ b/fs/cifs/inode.c @@ -1831,11 +1831,11 @@ cifs_invalidate_mapping(struct inode *inode) * @word: long word containing the bit lock */ static int -cifs_wait_bit_killable(struct wait_bit_key *key) +cifs_wait_bit_killable(struct wait_bit_key *key, int mode) { - if (fatal_signal_pending(current)) - return -ERESTARTSYS; freezable_schedule_unsafe(); + if (signal_pending_state(mode, current)) + return -ERESTARTSYS; return 0; } diff --git a/fs/nfs/inode.c b/fs/nfs/inode.c index 31b0a52..c7e8b87 100644 --- a/fs/nfs/inode.c +++ b/fs/nfs/inode.c @@ -75,11 +75,11 @@ nfs_fattr_to_ino_t(struct nfs_fattr *fattr) * nfs_wait_bit_killable - helper for functions that are sleeping on bit locks * @word: long word containing the bit lock */ -int nfs_wait_bit_killable(struct wait_bit_key *key) +int nfs_wait_bit_killable(struct wait_bit_key *key, int mode) { - if (fatal_signal_pending(current)) - return -ERESTARTSYS; freezable_schedule_unsafe(); + if (signal_pending_state(mode, current)) + return -ERESTARTSYS; return 0; } EXPORT_SYMBOL_GPL(nfs_wait_bit_killable); diff --git a/fs/nfs/internal.h b/fs/nfs/internal.h index 56cfde2..9dea85f 100644 --- a/fs/nfs/internal.h +++ b/fs/nfs/internal.h @@ -379,7 +379,7 @@ extern int nfs_drop_inode(struct inode *); extern void nfs_clear_inode(struct inode *); extern void nfs_evict_inode(struct inode *); void nfs_zap_acl_cache(struct inode *inode); -extern int nfs_wait_bit_killable(struct wait_bit_key *key); +extern int nfs_wait_bit_killable(struct wait_bit_key *key, int mode); /* super.c */ extern const struct super_operations nfs_sops; diff --git a/fs/nfs/pagelist.c b/fs/nfs/pagelist.c index fe3ddd2..452a011 100644 --- a/fs/nfs/pagelist.c +++ b/fs/nfs/pagelist.c @@ -129,7 +129,7 @@ __nfs_iocounter_wait(struct nfs_io_counter *c) set_bit(NFS_IO_INPROGRESS, &c->flags); if (atomic_read(&c->io_count) == 0) break; - ret = nfs_wait_bit_killable(&q.key); + ret = nfs_wait_bit_killable(&q.key, TASK_KILLABLE); } while (atomic_read(&c->io_count) != 0 && !ret); finish_wait(wq, &q.wait); return ret; diff --git a/fs/nfs/pnfs.c b/fs/nfs/pnfs.c index 5a8ae21..bec0384 100644 --- a/fs/nfs/pnfs.c +++ b/fs/nfs/pnfs.c @@ -1466,11 +1466,11 @@ static bool pnfs_within_mdsthreshold(struct nfs_open_context *ctx, } /* stop waiting if someone clears NFS_LAYOUT_RETRY_LAYOUTGET bit. */ -static int pnfs_layoutget_retry_bit_wait(struct wait_bit_key *key) +static int pnfs_layoutget_retry_bit_wait(struct wait_bit_key *key, int mode) { if (!test_bit(NFS_LAYOUT_RETRY_LAYOUTGET, key->flags)) return 1; - return nfs_wait_bit_killable(key); + return nfs_wait_bit_killable(key, mode); } static bool pnfs_prepare_to_retry_layoutget(struct pnfs_layout_hdr *lo) diff --git a/include/linux/wait.h b/include/linux/wait.h index 1e1bf9f..513b36f 100644 --- a/include/linux/wait.h +++ b/include/linux/wait.h @@ -145,7 +145,7 @@ __remove_wait_queue(wait_queue_head_t *head, wait_queue_t *old) list_del(&old->task_list); } -typedef int wait_bit_action_f(struct wait_bit_key *); +typedef int wait_bit_action_f(struct wait_bit_key *, int mode); void __wake_up(wait_queue_head_t *q, unsigned int mode, int nr, void *key); void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key); void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, void *key); @@ -960,10 +960,10 @@ int wake_bit_function(wait_queue_t *wait, unsigned mode, int sync, void *key); } while (0) -extern int bit_wait(struct wait_bit_key *); -extern int bit_wait_io(struct wait_bit_key *); -extern int bit_wait_timeout(struct wait_bit_key *); -extern int bit_wait_io_timeout(struct wait_bit_key *); +extern int bit_wait(struct wait_bit_key *, int); +extern int bit_wait_io(struct wait_bit_key *, int); +extern int bit_wait_timeout(struct wait_bit_key *, int); +extern int bit_wait_io_timeout(struct wait_bit_key *, int); /** * wait_on_bit - wait for a bit to be cleared diff --git a/kernel/sched/wait.c b/kernel/sched/wait.c index f10bd87..f15d6b6 100644 --- a/kernel/sched/wait.c +++ b/kernel/sched/wait.c @@ -392,7 +392,7 @@ __wait_on_bit(wait_queue_head_t *wq, struct wait_bit_queue *q, do { prepare_to_wait(wq, &q->wait, mode); if (test_bit(q->key.bit_nr, q->key.flags)) - ret = (*action)(&q->key); + ret = (*action)(&q->key, mode); } while (test_bit(q->key.bit_nr, q->key.flags) && !ret); finish_wait(wq, &q->wait); return ret; @@ -431,7 +431,7 @@ __wait_on_bit_lock(wait_queue_head_t *wq, struct wait_bit_queue *q, prepare_to_wait_exclusive(wq, &q->wait, mode); if (!test_bit(q->key.bit_nr, q->key.flags)) continue; - ret = action(&q->key); + ret = action(&q->key, mode); if (!ret) continue; abort_exclusive_wait(wq, &q->wait, mode, &q->key); @@ -581,43 +581,43 @@ void wake_up_atomic_t(atomic_t *p) } EXPORT_SYMBOL(wake_up_atomic_t); -__sched int bit_wait(struct wait_bit_key *word) +__sched int bit_wait(struct wait_bit_key *word, int mode) { schedule(); - if (signal_pending(current)) + if (signal_pending_state(mode, current)) return -EINTR; return 0; } EXPORT_SYMBOL(bit_wait); -__sched int bit_wait_io(struct wait_bit_key *word) +__sched int bit_wait_io(struct wait_bit_key *word, int mode) { io_schedule(); - if (signal_pending(current)) + if (signal_pending_state(mode, current)) return -EINTR; return 0; } EXPORT_SYMBOL(bit_wait_io); -__sched int bit_wait_timeout(struct wait_bit_key *word) +__sched int bit_wait_timeout(struct wait_bit_key *word, int mode) { unsigned long now = READ_ONCE(jiffies); if (time_after_eq(now, word->timeout)) return -EAGAIN; schedule_timeout(word->timeout - now); - if (signal_pending(current)) + if (signal_pending_state(mode, current)) return -EINTR; return 0; } EXPORT_SYMBOL_GPL(bit_wait_timeout); -__sched int bit_wait_io_timeout(struct wait_bit_key *word) +__sched int bit_wait_io_timeout(struct wait_bit_key *word, int mode) { unsigned long now = READ_ONCE(jiffies); if (time_after_eq(now, word->timeout)) return -EAGAIN; io_schedule_timeout(word->timeout - now); - if (signal_pending(current)) + if (signal_pending_state(mode, current)) return -EINTR; return 0; } diff --git a/net/sunrpc/sched.c b/net/sunrpc/sched.c index f14f24e..73ad57a 100644 --- a/net/sunrpc/sched.c +++ b/net/sunrpc/sched.c @@ -250,11 +250,11 @@ void rpc_destroy_wait_queue(struct rpc_wait_queue *queue) } EXPORT_SYMBOL_GPL(rpc_destroy_wait_queue); -static int rpc_wait_bit_killable(struct wait_bit_key *key) +static int rpc_wait_bit_killable(struct wait_bit_key *key, int mode) { - if (fatal_signal_pending(current)) - return -ERESTARTSYS; freezable_schedule_unsafe(); + if (signal_pending_state(mode, current)) + return -ERESTARTSYS; return 0; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/