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Message-Id: <20071219220307.d69c0fde.akpm@linux-foundation.org>
Date: Wed, 19 Dec 2007 22:03:07 -0800
From: Andrew Morton <akpm@...ux-foundation.org>
To: Miles Lane <miles.lane@...il.com>
Cc: LKML <linux-kernel@...r.kernel.org>,
Ingo Molnar <mingo@...hat.com>,
Russell King <rmk+lkml@....linux.org.uk>,
David Howells <dhowells@...hat.com>
Subject: Re: OOPS: 2.6.24-rc5-mm1 -- EIP is at r_show+0x2a/0x70 --
(triggered by "cat /proc/iomem")
On Thu, 20 Dec 2007 00:35:51 -0500 Miles Lane <miles.lane@...il.com> wrote:
> Added Ingo and Russell to the TO list, since they seem to potentially be
> the right people to look into this.
> .config attached in order to not trip spam filters.
>
> Miles Lane wrote:
> > Okay. The command that directly triggers this is: cat /proc/iomem
> >
> > Here is the stack trace without the line-wrapping (sorry!):
> >
> > [ 251.602965] wlan0_rename: RX non-WEP frame, but expected encryption
> > [ 252.868386] BUG: unable to handle kernel NULL pointer dereference
> > at virtual address 00000018
> > [ 252.868393] printing ip: c012d527 *pde = 00000000
> > [ 252.868399] Oops: 0000 [#1] SMP
> > [ 252.868403] last sysfs file:
> > /sys/devices/pci0000:00/0000:00:1f.2/host0/target0:0:0/0:0:0:0/block/sda/sda3/stat
> >
> > [ 252.868407] Modules linked in: aes_i586 aes_generic i915 drm rfcomm
> > l2cap bluetooth acpi_cpufreq cpufreq_stats cpufreq_conservative sbs
> > sbshc dm_crypt sbp2 parport_pc lp parport arc4 ecb crypto_blkcipher
> > cryptomgr crypto_algapi snd_hda_intel snd_pcm_oss snd_mixer_oss pcmcia
> > snd_pcm iTCO_wdt iTCO_vendor_support snd_seq_dummy watchdog_core
> > watchdog_dev snd_seq_oss snd_seq_midi tifm_7xx1 snd_rawmidi iwl3945
> > snd_seq_midi_event rng_core tifm_core mac80211 snd_seq snd_timer
> > snd_seq_device cfg80211 sky2 battery yenta_socket rsrc_nonstatic
> > pcmcia_core ac snd soundcore snd_page_alloc button shpchp pci_hotplug
> > sr_mod cdrom pata_acpi piix ide_core firewire_ohci firewire_core
> > crc_itu_t thermal processor fan
> > [ 252.868469]
> > [ 252.868472] Pid: 7088, comm: head Not tainted (2.6.24-rc5-mm1 #9)
> > [ 252.868476] EIP: 0060:[<c012d527>] EFLAGS: 00010297 CPU: 0
> > [ 252.868481] EIP is at r_show+0x2a/0x70
> > [ 252.868483] EAX: 00000000 EBX: 00000001 ECX: c07e3224 EDX: c04bb034
> > [ 252.868486] ESI: 00000008 EDI: ed1f52c0 EBP: f5320f10 ESP: f5320f04
> > [ 252.868489] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068
> > [ 252.868493] Process head (pid: 7088, ti=f5320000 task=f532e000
> > task.ti=f5320000)
> > [ 252.868495] Stack: c03a6cac ed1f52c0 c07e3224 f5320f50 c0199a7e
> > 00002000 bf930807 e1007800
> > [ 252.868504] ed1f52e0 00000000 00000000 000001d3 0000000e
> > 00000000 0000000d 00000000
> > [ 252.868512] fffffffb f7d39370 c01998e4 f5320f74 c01af4f5
> > f5320f9c 00002000 bf930807
> > [ 252.868521] Call Trace:
> > [ 252.868523] [<c0107d55>] show_trace_log_lvl+0x12/0x25
> > [ 252.868529] [<c0107df2>] show_stack_log_lvl+0x8a/0x95
> > [ 252.868534] [<c0107e89>] show_registers+0x8c/0x154
> > [ 252.868538] [<c010805f>] die+0x10e/0x1d2
> > [ 252.868542] [<c039c8c9>] do_page_fault+0x52b/0x600
> > [ 252.868547] [<c039af9a>] error_code+0x72/0x78
> > [ 252.868552] [<c0199a7e>] seq_read+0x19a/0x26c
> > [ 252.868557] [<c01af4f5>] proc_reg_read+0x60/0x74
> > [ 252.868562] [<c018390d>] vfs_read+0xa2/0x11e
> > [ 252.868567] [<c0183d02>] sys_read+0x3b/0x60
> > [ 252.868571] [<c0106bae>] sysenter_past_esp+0x6b/0xc1
> > [ 252.868575] =======================
> > [ 252.868577] Code: c3 55 89 d1 89 e5 57 89 c7 56 53 8b 50 64 83 7a
> > 0c 00 77 0e 81 7a 08 ff ff 00 00 be 04 00 00 00 76 05 be 08 00 00 00
> > 89 c8 31 db <8b> 40 18 39 d0 74 06 43 83 fb 05 75 f3 8b 41 10 ba 2f 1b
> > 45 c0
> > [ 252.868623] EIP: [<c012d527>] r_show+0x2a/0x70 SS:ESP 0068:f5320f04
> >
> >
I would be suspecting iget-stop-procfs-from-using-iget-and-read_inode.patch.
Here's a (tested) revert of various bits. Can you please try it against
2.6.24-rc5-mm1?
Thanks.
Documentation/filesystems/Locking | 3 +
Documentation/filesystems/porting | 12 ++---
Documentation/filesystems/vfs.txt | 17 ++++++-
fs/inode.c | 4 +
fs/proc/inode.c | 60 ++++++++++++++--------------
include/linux/fs.h | 14 ++++++
6 files changed, 73 insertions(+), 37 deletions(-)
diff -puN fs/proc/inode.c~revert-iget-stop-procfs-from-using-iget-and-read_inode-checkpatch-fixes fs/proc/inode.c
--- a/fs/proc/inode.c~revert-iget-stop-procfs-from-using-iget-and-read_inode-checkpatch-fixes
+++ a/fs/proc/inode.c
@@ -73,6 +73,11 @@ static void proc_delete_inode(struct ino
struct vfsmount *proc_mnt;
+static void proc_read_inode(struct inode * inode)
+{
+ inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
+}
+
static struct kmem_cache * proc_inode_cachep;
static struct inode *proc_alloc_inode(struct super_block *sb)
@@ -123,6 +128,7 @@ static int proc_remount(struct super_blo
static const struct super_operations proc_sops = {
.alloc_inode = proc_alloc_inode,
.destroy_inode = proc_destroy_inode,
+ .read_inode = proc_read_inode,
.drop_inode = generic_delete_inode,
.delete_inode = proc_delete_inode,
.statfs = simple_statfs,
@@ -395,41 +401,39 @@ struct inode *proc_get_inode(struct supe
if (de != NULL && !try_module_get(de->owner))
goto out_mod;
- inode = iget_locked(sb, ino);
+ inode = iget(sb, ino);
if (!inode)
goto out_ino;
- if (inode->i_state & I_NEW) {
- inode->i_mtime = inode->i_atime = inode->i_ctime = CURRENT_TIME;
- PROC_I(inode)->fd = 0;
- PROC_I(inode)->pde = de;
- if (de) {
- if (de->mode) {
- inode->i_mode = de->mode;
- inode->i_uid = de->uid;
- inode->i_gid = de->gid;
- }
- if (de->size)
- inode->i_size = de->size;
- if (de->nlink)
- inode->i_nlink = de->nlink;
- if (de->proc_iops)
- inode->i_op = de->proc_iops;
- if (de->proc_fops) {
- if (S_ISREG(inode->i_mode)) {
+
+ PROC_I(inode)->fd = 0;
+ PROC_I(inode)->pde = de;
+ if (de) {
+ if (de->mode) {
+ inode->i_mode = de->mode;
+ inode->i_uid = de->uid;
+ inode->i_gid = de->gid;
+ }
+ if (de->size)
+ inode->i_size = de->size;
+ if (de->nlink)
+ inode->i_nlink = de->nlink;
+ if (de->proc_iops)
+ inode->i_op = de->proc_iops;
+ if (de->proc_fops) {
+ if (S_ISREG(inode->i_mode)) {
#ifdef CONFIG_COMPAT
- if (!de->proc_fops->compat_ioctl)
- inode->i_fop =
- &proc_reg_file_ops_no_compat;
- else
+ if (!de->proc_fops->compat_ioctl)
+ inode->i_fop =
+ &proc_reg_file_ops_no_compat;
+ else
#endif
- inode->i_fop = &proc_reg_file_ops;
- } else {
- inode->i_fop = de->proc_fops;
- }
+ inode->i_fop = &proc_reg_file_ops;
}
+ else
+ inode->i_fop = de->proc_fops;
}
- unlock_new_inode(inode);
}
+
return inode;
out_ino:
diff -puN Documentation/filesystems/Locking~revert-iget-stop-procfs-from-using-iget-and-read_inode-checkpatch-fixes Documentation/filesystems/Locking
--- a/Documentation/filesystems/Locking~revert-iget-stop-procfs-from-using-iget-and-read_inode-checkpatch-fixes
+++ a/Documentation/filesystems/Locking
@@ -90,6 +90,7 @@ of the locking scheme for directory oper
prototypes:
struct inode *(*alloc_inode)(struct super_block *sb);
void (*destroy_inode)(struct inode *);
+ void (*read_inode) (struct inode *);
void (*dirty_inode) (struct inode *);
int (*write_inode) (struct inode *, int);
void (*put_inode) (struct inode *);
@@ -113,6 +114,7 @@ locking rules:
BKL s_lock s_umount
alloc_inode: no no no
destroy_inode: no
+read_inode: no (see below)
dirty_inode: no (must not sleep)
write_inode: no
put_inode: no
@@ -131,6 +133,7 @@ show_options: no (vfsmount->sem)
quota_read: no no no (see below)
quota_write: no no no (see below)
+->read_inode() is not a method - it's a callback used in iget().
->remount_fs() will have the s_umount lock if it's already mounted.
When called from get_sb_single, it does NOT have the s_umount lock.
->quota_read() and ->quota_write() functions are both guaranteed to
diff -puN Documentation/filesystems/porting~revert-iget-stop-procfs-from-using-iget-and-read_inode-checkpatch-fixes Documentation/filesystems/porting
--- a/Documentation/filesystems/porting~revert-iget-stop-procfs-from-using-iget-and-read_inode-checkpatch-fixes
+++ a/Documentation/filesystems/porting
@@ -34,8 +34,8 @@ FOO_I(inode) (see in-tree filesystems fo
Make them ->alloc_inode and ->destroy_inode in your super_operations.
-Keep in mind that now you need explicit initialization of private data
-typically between calling iget_locked() and unlocking the inode.
+Keep in mind that now you need explicit initialization of private data -
+typically in ->read_inode() and after getting an inode from new_inode().
At some point that will become mandatory.
@@ -173,10 +173,10 @@ should be a non-blocking function that i
newly created inode to allow the test function to succeed. 'data' is
passed as an opaque value to both test and set functions.
-When the inode has been created by iget5_locked(), it will be returned with the
-I_NEW flag set and will still be locked. The filesystem then needs to finalize
-the initialization. Once the inode is initialized it must be unlocked by
-calling unlock_new_inode().
+When the inode has been created by iget5_locked(), it will be returned with
+the I_NEW flag set and will still be locked. read_inode has not been
+called so the file system still has to finalize the initialization. Once
+the inode is initialized it must be unlocked by calling unlock_new_inode().
The filesystem is responsible for setting (and possibly testing) i_ino
when appropriate. There is also a simpler iget_locked function that
diff -puN Documentation/filesystems/vfs.txt~revert-iget-stop-procfs-from-using-iget-and-read_inode-checkpatch-fixes Documentation/filesystems/vfs.txt
--- a/Documentation/filesystems/vfs.txt~revert-iget-stop-procfs-from-using-iget-and-read_inode-checkpatch-fixes
+++ a/Documentation/filesystems/vfs.txt
@@ -203,6 +203,8 @@ struct super_operations {
struct inode *(*alloc_inode)(struct super_block *sb);
void (*destroy_inode)(struct inode *);
+ void (*read_inode) (struct inode *);
+
void (*dirty_inode) (struct inode *);
int (*write_inode) (struct inode *, int);
void (*put_inode) (struct inode *);
@@ -240,6 +242,15 @@ or bottom half).
->alloc_inode was defined and simply undoes anything done by
->alloc_inode.
+ read_inode: this method is called to read a specific inode from the
+ mounted filesystem. The i_ino member in the struct inode is
+ initialized by the VFS to indicate which inode to read. Other
+ members are filled in by this method.
+
+ You can set this to NULL and use iget5_locked() instead of iget()
+ to read inodes. This is necessary for filesystems for which the
+ inode number is not sufficient to identify an inode.
+
dirty_inode: this method is called by the VFS to mark an inode dirty.
write_inode: this method is called when the VFS needs to write an
@@ -297,9 +308,9 @@ or bottom half).
quota_write: called by the VFS to write to filesystem quota file.
-Whoever sets up the inode is responsible for filling in the "i_op" field. This
-is a pointer to a "struct inode_operations" which describes the methods that
-can be performed on individual inodes.
+The read_inode() method is responsible for filling in the "i_op"
+field. This is a pointer to a "struct inode_operations" which
+describes the methods that can be performed on individual inodes.
The Inode Object
diff -puN fs/inode.c~revert-iget-stop-procfs-from-using-iget-and-read_inode-checkpatch-fixes fs/inode.c
--- a/fs/inode.c~revert-iget-stop-procfs-from-using-iget-and-read_inode-checkpatch-fixes
+++ a/fs/inode.c
@@ -928,6 +928,8 @@ EXPORT_SYMBOL(ilookup);
* @set: callback used to initialize a new struct inode
* @data: opaque data pointer to pass to @test and @set
*
+ * This is iget() without the read_inode() portion of get_new_inode().
+ *
* iget5_locked() uses ifind() to search for the inode specified by @hashval
* and @data in the inode cache and if present it is returned with an increased
* reference count. This is a generalized version of iget_locked() for file
@@ -964,6 +966,8 @@ EXPORT_SYMBOL(iget5_locked);
* @sb: super block of file system
* @ino: inode number to get
*
+ * This is iget() without the read_inode() portion of get_new_inode_fast().
+ *
* iget_locked() uses ifind_fast() to search for the inode specified by @ino in
* the inode cache and if present it is returned with an increased reference
* count. This is for file systems where the inode number is sufficient for
diff -puN include/linux/fs.h~revert-iget-stop-procfs-from-using-iget-and-read_inode-checkpatch-fixes include/linux/fs.h
--- a/include/linux/fs.h~revert-iget-stop-procfs-from-using-iget-and-read_inode-checkpatch-fixes
+++ a/include/linux/fs.h
@@ -1241,6 +1241,8 @@ struct super_operations {
struct inode *(*alloc_inode)(struct super_block *sb);
void (*destroy_inode)(struct inode *);
+ void (*read_inode) (struct inode *);
+
void (*dirty_inode) (struct inode *);
int (*write_inode) (struct inode *, int);
void (*put_inode) (struct inode *);
@@ -1752,6 +1754,18 @@ extern struct inode * iget5_locked(struc
extern struct inode * iget_locked(struct super_block *, unsigned long);
extern void unlock_new_inode(struct inode *);
+static inline struct inode *iget(struct super_block *sb, unsigned long ino)
+{
+ struct inode *inode = iget_locked(sb, ino);
+
+ if (inode && (inode->i_state & I_NEW)) {
+ sb->s_op->read_inode(inode);
+ unlock_new_inode(inode);
+ }
+
+ return inode;
+}
+
extern void __iget(struct inode * inode);
extern void iget_failed(struct inode *);
extern void clear_inode(struct inode *);
_
--
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