| Message ID | 1431533401-28810-1-git-send-email-avagin@openvz.org (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
2015-05-13 19:10 GMT+03:00 Andrey Vagin <avagin@openvz.org>: > The context can't be switched in rcu critical sections. Here is a warning which I see in dmesg without this patch: [20570.684805] =============================== [20570.685983] [ INFO: suspicious RCU usage. ] [20570.687011] 4.1.0-rc3-next-20150513+ #236 Not tainted [20570.688295] ------------------------------- [20570.689277] include/linux/rcupdate.h:568 Illegal context switch in RCU read-side critical section! [20570.691550] other info that might help us debug this: [20570.693628] rcu_scheduler_active = 1, debug_locks = 0 [20570.695430] 1 lock held by systemd/1: [20570.696455] #0: (rcu_read_lock){......}, at: [<ffffffff812166ba>] path_init+0x54a/0x920 [20570.698734] stack backtrace: [20570.699896] CPU: 3 PID: 1 Comm: systemd Not tainted 4.1.0-rc3-next-20150513+ #236 [20570.701824] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 [20570.703322] 0000000000000000 00000000719ddd62 ffff88007d0ffaa8 ffffffff8175e78d [20570.705453] 0000000000000000 ffff88007d160000 ffff88007d0ffad8 ffffffff810d8b17 [20570.707485] ffff88007fd96e40 0000000000016e40 ffff88007fd96e40 ffff88007b828868 [20570.709540] Call Trace: [20570.710231] [<ffffffff8175e78d>] dump_stack+0x45/0x57 [20570.711573] [<ffffffff810d8b17>] lockdep_rcu_suspicious+0xd7/0x110 [20570.713211] [<ffffffff81760da3>] __schedule+0x4b3/0xbf0 [20570.714553] [<ffffffff81214714>] ? generic_permission+0x24/0x1c0 [20570.716241] [<ffffffff817617d2>] preempt_schedule_common+0x22/0x40 [20570.717873] [<ffffffff81761811>] _cond_resched+0x21/0x30 [20570.719287] [<ffffffff81217d43>] link_path_walk+0x1f3/0x6a0 [20570.720785] [<ffffffff812188f6>] ? path_lookupat+0x16/0xf0 [20570.722260] [<ffffffff8121b544>] ? getname_kernel+0x34/0x130 [20570.723785] [<ffffffff8121895c>] path_lookupat+0x7c/0xf0 [20570.725301] [<ffffffff8121b544>] ? getname_kernel+0x34/0x130 [20570.726790] [<ffffffff81218a3e>] filename_lookup+0x6e/0x120 [20570.728264] [<ffffffff8121b941>] kern_path+0x51/0xb0 [20570.729584] [<ffffffff8161ced1>] ? __kmalloc_reserve.isra.34+0x31/0x80 [20570.731291] [<ffffffff816f9187>] unix_find_other+0x47/0x230 [20570.732762] [<ffffffff816f9d4a>] unix_stream_connect+0xfa/0x4c0 [20570.734364] [<ffffffff816133c7>] SYSC_connect+0xe7/0x120 [20570.735812] [<ffffffff813b0cc5>] ? lockdep_sys_exit_thunk+0x12/0x14 [20570.737475] [<ffffffff8161476e>] SyS_connect+0xe/0x10 [20570.738830] [<ffffffff8176782e>] system_call_fastpath+0x12/0x76 > > Cc: NeilBrown <neilb@suse.de> > Cci: Al Viro <viro@zeniv.linux.org.uk> > Fixes: 26c59f88c223 ("VFS/namei: make the use of touch_atime() in get_link() RCU-safe.") > Signed-off-by: Andrey Vagin <avagin@openvz.org> > --- > fs/namei.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/fs/namei.c b/fs/namei.c > index f884ddd..0ef3c79 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -967,14 +967,13 @@ const char *get_link(struct nameidata *nd) > > if (!(nd->flags & LOOKUP_RCU)) { > touch_atime(&last->link); > + _cond_resched(); > } else if (atime_needs_update(&last->link, inode)) { > if (unlikely(unlazy_walk(nd, NULL, 0))) > return ERR_PTR(-ECHILD); > touch_atime(&last->link); > } > > - _cond_resched(); > - > error = security_inode_follow_link(dentry, inode, > nd->flags & LOOKUP_RCU); > if (unlikely(error)) > -- > 2.1.0 > -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, May 13, 2015 at 07:10:01PM +0300, Andrey Vagin wrote:
> The context can't be switched in rcu critical sections.
Folded in a slightly different form and force-pushed.
--
To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/fs/namei.c b/fs/namei.c index f884ddd..0ef3c79 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -967,14 +967,13 @@ const char *get_link(struct nameidata *nd) if (!(nd->flags & LOOKUP_RCU)) { touch_atime(&last->link); + _cond_resched(); } else if (atime_needs_update(&last->link, inode)) { if (unlikely(unlazy_walk(nd, NULL, 0))) return ERR_PTR(-ECHILD); touch_atime(&last->link); } - _cond_resched(); - error = security_inode_follow_link(dentry, inode, nd->flags & LOOKUP_RCU); if (unlikely(error))
The context can't be switched in rcu critical sections. Cc: NeilBrown <neilb@suse.de> Cci: Al Viro <viro@zeniv.linux.org.uk> Fixes: 26c59f88c223 ("VFS/namei: make the use of touch_atime() in get_link() RCU-safe.") Signed-off-by: Andrey Vagin <avagin@openvz.org> --- fs/namei.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)