Message ID | 20150121200626.GR29656@ZenIV.linux.org.uk (mailing list archive) |
---|---|
State | New, archived |
Headers | show |
On 01/21/2015 12:06 PM, Al Viro wrote: > On Wed, Jan 21, 2015 at 11:06:27AM -0800, Guenter Roeck wrote: >> On 01/21/2015 10:29 AM, Al Viro wrote: >>> On Wed, Jan 21, 2015 at 05:32:13AM -0800, Guenter Roeck wrote: >>>> Another data point (though I have no idea if it is useful or what it means): >>>> >>>> In the working case, path_init sets nd->flags to 0x50 or 0x51. >>>> In the non-working case (ie for all files with a '/' in the name), >>>> it sets nd->flags to 0x10 or 0x11, even though it is always called >>>> with the LOOKUP_RCU bit set in flags. >>> >>> Umm... Are those path_init() succeeding or failing? Note that path_init() >>> includes "walk everything except for the last component", so your non-working >>> case is "have it walk anything at all". What's failing there? path_init() >>> or handling the remaining component? >>> >> path_init() returns -2. Guess that explains the unexpected flags ;-). >> The failuere is from >> link_path_walk() >> walk_component() > > Which is to say, lookup gave it a negative dentry. OK, let's just make > vfs_mkdir() and walk_component() print what they are doing; on top of > linux-next > > diff --git a/fs/namei.c b/fs/namei.c > index 323957f..8a4e22f 100644 > --- a/fs/namei.c > +++ b/fs/namei.c > @@ -1586,8 +1586,11 @@ static inline int walk_component(struct nameidata *nd, struct path *path, > inode = path->dentry->d_inode; > } > err = -ENOENT; > - if (!inode || d_is_negative(path->dentry)) > + if (!inode || d_is_negative(path->dentry)) { > + printk(KERN_ERR "walk_component[%p,%pd4] -> negative\n", > + path->dentry, path->dentry); > goto out_path_put; > + } > > if (should_follow_link(path->dentry, follow)) { > if (nd->flags & LOOKUP_RCU) { > @@ -3521,6 +3524,7 @@ int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) > error = dir->i_op->mkdir(dir, dentry, mode); > if (!error) > fsnotify_mkdir(dir, dentry); > + printk(KERN_ERR "mkdir[%p,%pd4] => %d\n", dentry, dentry, error); > return error; > } > EXPORT_SYMBOL(vfs_mkdir); > ok case (putname commented out): user_path_at_empty lookup usr flags 0x0 path_lookupat: calling path_init 'usr' flags=40 path_init: link_path_walk() returned 0 path_lookupat: path_init 'usr' flags=40[50] returned 0 walk_component: lookup_fast() returned 1 walk_component: lookup_slow() returned 0 walk_component: inode= (null), negative=1 do_path_lookup(usr, 0x10) path_lookupat: calling path_init 'usr' flags=50 path_init: link_path_walk() returned 0 path_lookupat: path_init 'usr' flags=50[50] returned 0 mkdir[c74012a0,/usr] => 0 user_path_at_empty lookup usr flags 0x1 path_lookupat: calling path_init 'usr' flags=41 path_init: link_path_walk() returned 0 path_lookupat: path_init 'usr' flags=41[51] returned 0 walk_component: inode=c74004a0, negative=0 user_path_at_empty lookup usr flags 0x1 path_lookupat: calling path_init 'usr' flags=41 path_init: link_path_walk() returned 0 path_lookupat: path_init 'usr' flags=41[51] returned 0 failing case: path_lookupat: calling path_init 'usr' flags=40 path_init: link_path_walk() returned 0 path_lookupat: path_init 'usr' flags=40[50] returned 0 walk_component: lookup_fast() returned 1 walk_component: lookup_slow() returned 0 walk_component: inode= (null), negative=1 do_path_lookup(usr, 0x10) path_lookupat: calling path_init 'usr' flags=50 path_init: link_path_walk() returned 0 path_lookupat: path_init 'usr' flags=50[50] returned 0 mkdir[c74012a0,/kkk] => 0 <==== SIC! user_path_at_empty lookup usr flags 0x1 path_lookupat: calling path_init 'usr' flags=41 path_init: link_path_walk() returned 0 path_lookupat: path_init 'usr' flags=41[51] returned 0 walk_component: lookup_fast() returned 1 walk_component: lookup_slow() returned 0 walk_component: inode= (null), negative=1 user_path_at_empty lookup usr flags 0x1 path_lookupat: calling path_init 'usr' flags=41 path_init: link_path_walk() returned 0 path_lookupat: path_init 'usr' flags=41[51] returned 0 walk_component: lookup_fast() returned 1 walk_component: lookup_slow() returned 0 walk_component: inode= (null), negative=1 Guenter -- 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
2015-01-21, 13:03:20 -0800, Guenter Roeck wrote: > On 01/21/2015 12:06 PM, Al Viro wrote: > >On Wed, Jan 21, 2015 at 11:06:27AM -0800, Guenter Roeck wrote: > >>On 01/21/2015 10:29 AM, Al Viro wrote: > >>>On Wed, Jan 21, 2015 at 05:32:13AM -0800, Guenter Roeck wrote: > >>>>Another data point (though I have no idea if it is useful or what it means): > >>>> > >>>>In the working case, path_init sets nd->flags to 0x50 or 0x51. > >>>>In the non-working case (ie for all files with a '/' in the name), > >>>>it sets nd->flags to 0x10 or 0x11, even though it is always called > >>>>with the LOOKUP_RCU bit set in flags. > >>> > >>>Umm... Are those path_init() succeeding or failing? Note that path_init() > >>>includes "walk everything except for the last component", so your non-working > >>>case is "have it walk anything at all". What's failing there? path_init() > >>>or handling the remaining component? > >>> > >>path_init() returns -2. Guess that explains the unexpected flags ;-). > >>The failuere is from > >> link_path_walk() > >> walk_component() > > > >Which is to say, lookup gave it a negative dentry. OK, let's just make > >vfs_mkdir() and walk_component() print what they are doing; on top of > >linux-next > > > >diff --git a/fs/namei.c b/fs/namei.c > >index 323957f..8a4e22f 100644 > >--- a/fs/namei.c > >+++ b/fs/namei.c > >@@ -1586,8 +1586,11 @@ static inline int walk_component(struct nameidata *nd, struct path *path, > > inode = path->dentry->d_inode; > > } > > err = -ENOENT; > >- if (!inode || d_is_negative(path->dentry)) > >+ if (!inode || d_is_negative(path->dentry)) { > >+ printk(KERN_ERR "walk_component[%p,%pd4] -> negative\n", > >+ path->dentry, path->dentry); > > goto out_path_put; > >+ } > > > > if (should_follow_link(path->dentry, follow)) { > > if (nd->flags & LOOKUP_RCU) { > >@@ -3521,6 +3524,7 @@ int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) > > error = dir->i_op->mkdir(dir, dentry, mode); > > if (!error) > > fsnotify_mkdir(dir, dentry); > >+ printk(KERN_ERR "mkdir[%p,%pd4] => %d\n", dentry, dentry, error); > > return error; > > } > > EXPORT_SYMBOL(vfs_mkdir); > > > > ok case (putname commented out): > > user_path_at_empty lookup usr flags 0x0 > path_lookupat: calling path_init 'usr' flags=40 > path_init: link_path_walk() returned 0 > path_lookupat: path_init 'usr' flags=40[50] returned 0 > walk_component: lookup_fast() returned 1 > walk_component: lookup_slow() returned 0 > walk_component: inode= (null), negative=1 > do_path_lookup(usr, 0x10) > path_lookupat: calling path_init 'usr' flags=50 > path_init: link_path_walk() returned 0 > path_lookupat: path_init 'usr' flags=50[50] returned 0 > mkdir[c74012a0,/usr] => 0 > user_path_at_empty lookup usr flags 0x1 > path_lookupat: calling path_init 'usr' flags=41 > path_init: link_path_walk() returned 0 > path_lookupat: path_init 'usr' flags=41[51] returned 0 > walk_component: inode=c74004a0, negative=0 > user_path_at_empty lookup usr flags 0x1 > path_lookupat: calling path_init 'usr' flags=41 > path_init: link_path_walk() returned 0 > path_lookupat: path_init 'usr' flags=41[51] returned 0 > > failing case: > > path_lookupat: calling path_init 'usr' flags=40 > path_init: link_path_walk() returned 0 > path_lookupat: path_init 'usr' flags=40[50] returned 0 > walk_component: lookup_fast() returned 1 > walk_component: lookup_slow() returned 0 > walk_component: inode= (null), negative=1 > do_path_lookup(usr, 0x10) > path_lookupat: calling path_init 'usr' flags=50 > path_init: link_path_walk() returned 0 > path_lookupat: path_init 'usr' flags=50[50] returned 0 > mkdir[c74012a0,/kkk] => 0 <==== SIC! > user_path_at_empty lookup usr flags 0x1 > path_lookupat: calling path_init 'usr' flags=41 > path_init: link_path_walk() returned 0 > path_lookupat: path_init 'usr' flags=41[51] returned 0 > walk_component: lookup_fast() returned 1 > walk_component: lookup_slow() returned 0 > walk_component: inode= (null), negative=1 > user_path_at_empty lookup usr flags 0x1 > path_lookupat: calling path_init 'usr' flags=41 > path_init: link_path_walk() returned 0 > path_lookupat: path_init 'usr' flags=41[51] returned 0 > walk_component: lookup_fast() returned 1 > walk_component: lookup_slow() returned 0 > walk_component: inode= (null), negative=1 Yep, I get some "kkk" too. With that patch: ## panic [ 0.544839] walk_component[ffff88001d6edbd8,/dev] -> negative [ 0.545507] mkdir[ffff88001d6ed1b8,/kkk] => 0 [ 0.545886] sys_mkdir dev:40755 returned 0 [ 0.546275] walk_component[ffff88001d6ec288,/dev] -> negative [ 0.546835] walk_component[ffff88001d6eca20,/dev] -> negative [ 0.547403] walk_component[ffff88001d6ed950,/dev] -> negative [ 0.547954] walk_component[ffff88001d6ed440,/dev] -> negative [ 0.549260] walk_component[ffff88001d6ec510,/dev] -> negative [ 0.551161] walk_component[ffff88001d6ec798,/dev] -> negative [ 0.551719] walk_component[ffff88001d6ed6c8,/dev] -> negative [ 0.552281] walk_component[ffff88001d6eef30,/root] -> negative [ 0.552866] mkdir[ffff88001d6ee000,/kkkk] => 0 [ 0.553254] sys_mkdir root:40700 returned 0 [ 0.553682] walk_component[ffff88001d6eeca8,/root] -> negative [ 0.554225] walk_component[ffff88001d6efbd8,/root] -> negative [ 0.554826] walk_component[ffff88001d6ef1b8,/root] -> negative [ 0.555390] walk_component[ffff88001d6ee288,/dev] -> negative [ 0.561523] walk_component[ffff88001d6eea20,/cpu] -> negative [ 0.562203] mkdir[ffff88001d6ef950,/kkk] => 0 [ 0.562627] walk_component[ffff88001d6ef440,/cpu] -> negative [ 0.819060] walk_component[ffff88001d6df1b8,/input] -> negative [ 0.819672] mkdir[ffff88001d6def30,/kkkkk] => 0 [ 0.820496] walk_component[ffff88001d6de510,/input] -> negative [ 0.840538] walk_component[ffff88001d6e6288,/dev] -> negative [ 0.841626] walk_component[ffff88001d6e6f30,/init] -> negative [ 0.992725] walk_component[ffff88001d6e6f30,/bsg] -> negative [ 0.993671] mkdir[ffff88001d6e6798,/kkk] => 0 [ 0.994307] walk_component[ffff88001d6e6288,/bsg] -> negative [ 1.007701] walk_component[ffff88001d6e6ca8,/bsg] -> negative [ 1.008561] walk_component[ffff88001d6e7950,/bsg] -> negative [ 1.024292] walk_component[ffff88001d6e7950,/dev] -> negative [ 1.025017] walk_component[ffff88001d6e7440,/dev] -> negative [ 1.025781] walk_component[ffff88001d6e6f30,/dev] -> negative [ 1.026495] walk_component[ffff88001d6e6510,/dev] -> negative [ 1.027243] walk_component[ffff88001d6e6288,/dev] -> negative [ 1.027910] stat("/dev/root") -> -2 [ 1.028358] walk_component[ffff88001d6df6c8,/dev] -> negative [ 1.029019] stat("dev") -> -2 [ 1.029431] walk_component[ffff88001d6df1b8,/root] -> negative ## good [ 0.350197] walk_component[ffff88001e348c80,/dev] -> negative [ 0.350821] mkdir[ffff88001e348dc0,/dev] => 0 [ 0.351467] sys_mkdir dev:40755 returned 0 [ 0.351919] walk_component[ffff88001e349000,/dev/console] -> negative [ 0.353000] walk_component[ffff88001e349280,/root] -> negative [ 0.353959] mkdir[ffff88001e3493c0,/root] => 0 [ 0.354354] sys_mkdir root:40700 returned 0 [ 0.357927] walk_component[ffff88001e349500,/cpu] -> negative [ 0.358470] mkdir[ffff88001e349640,/cpu] => 0 [ 0.472772] walk_component[ffff88001e34ba00,/input] -> negative [ 0.473392] mkdir[ffff88001e34bb40,/input] => 0 [ 0.478682] walk_component[ffff88001e34cdc0,/init] -> negative [ 0.647559] walk_component[ffff88001e34cdc0,/bsg] -> negative [ 0.648671] mkdir[ffff88001e34ba00,/bsg] => 0 [ 0.665831] stat("/dev/root") -> 0 [ 0.666360] stat("dev") -> 0 Another thing, not sure if it's relevant: I can boot with the do_lookup_path patch applied, and without commenting out putname(), if I disable SLUB debugging with slub_debug=- (with CONFIG_SLUB_DEBUG=y CONFIG_SLUB_DEBUG_ON=y)
diff --git a/fs/namei.c b/fs/namei.c index 323957f..8a4e22f 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -1586,8 +1586,11 @@ static inline int walk_component(struct nameidata *nd, struct path *path, inode = path->dentry->d_inode; } err = -ENOENT; - if (!inode || d_is_negative(path->dentry)) + if (!inode || d_is_negative(path->dentry)) { + printk(KERN_ERR "walk_component[%p,%pd4] -> negative\n", + path->dentry, path->dentry); goto out_path_put; + } if (should_follow_link(path->dentry, follow)) { if (nd->flags & LOOKUP_RCU) { @@ -3521,6 +3524,7 @@ int vfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode) error = dir->i_op->mkdir(dir, dentry, mode); if (!error) fsnotify_mkdir(dir, dentry); + printk(KERN_ERR "mkdir[%p,%pd4] => %d\n", dentry, dentry, error); return error; } EXPORT_SYMBOL(vfs_mkdir);