> -----Original Message----- > From: J. R. Okajima [mailto:hooanon05@xxxxxxxxxxx] > Sent: Thursday, January 13, 2011 6:52 PM > To: Mark Brown > Cc: Trond Myklebust; Santosh Shilimkar; Nick Piggin; linux- > nfs@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; linux- > fsdevel@xxxxxxxxxxxxxxx > Subject: Re: NFS root lockups with -next 20110113 > > > Mark Brown: > > With -next 20110113 I'm experiencing lockups shortly after > userspace > > starts when booting with my root filesystem on NFS, log below. I > can > > boot into /bin/sh but running real userspace triggers this very > easily. > > This was introduced sometime this week. > > > > I've not bisected or otherwise investigated much yet, but I do > notice > > code added recently by Nick in "fs: rcu-walk for path lookup" > showing up > > in the backtrace so including him in the CCs. > > This and a report from Santosh Shilimkar look like the same problem > which I reported, and I am testing this patch. If you can, please > try it > too. > Note: Of course this is not offcial fix. > It works. My board booted with NFS with below patch > > diff --git a/fs/namei.c b/fs/namei.c > index 5bb7588..51d052f 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -480,6 +480,7 @@ static int nameidata_dentry_drop_rcu(struct > nameidata *nd, struct dentry *dentry > { > struct fs_struct *fs = current->fs; > struct dentry *parent = nd->path.dentry; > + int isroot; > > BUG_ON(!(nd->flags & LOOKUP_RCU)); > if (nd->root.mnt) { > @@ -489,18 +490,22 @@ static int nameidata_dentry_drop_rcu(struct > nameidata *nd, struct dentry *dentry > goto err_root; > } > spin_lock(&parent->d_lock); > - spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); > - if (!__d_rcu_to_refcount(dentry, nd->seq)) > - goto err; > + isroot = IS_ROOT(dentry); > + if (!isroot) { > + spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED); > + if (!__d_rcu_to_refcount(dentry, nd->seq)) > + goto err; > + } > /* > * If the sequence check on the child dentry passed, then the > child has > * not been removed from its parent. This means the parent > dentry must > * be valid and able to take a reference at this point. > */ > - BUG_ON(!IS_ROOT(dentry) && dentry->d_parent != parent); > + BUG_ON(!isroot && dentry->d_parent != parent); > BUG_ON(!parent->d_count); > parent->d_count++; > - spin_unlock(&dentry->d_lock); > + if (!isroot) > + spin_unlock(&dentry->d_lock); > spin_unlock(&parent->d_lock); > if (nd->root.mnt) { > path_get(&nd->root); > @@ -513,7 +518,8 @@ static int nameidata_dentry_drop_rcu(struct > nameidata *nd, struct dentry *dentry > nd->flags &= ~LOOKUP_RCU; > return 0; > err: > - spin_unlock(&dentry->d_lock); > + if (!isroot) > + spin_unlock(&dentry->d_lock); > spin_unlock(&parent->d_lock); > err_root: > if (nd->root.mnt) -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
