mm/memory: print also a_ops->readpage in print_bad_pte

PATCH In review Konstantin Khlebnikov 4 participants 6 messages Apr 3, 2015 – Apr 4, 2015

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Konstantin Khlebnikov

author

2015-04-03 17:18 UTC #0 lore raw

PATCH 1/1 mm/memory: print also a_ops->readpage in print_bad_pte

A lot of filesystems use generic_file_mmap() and filemap_fault(), f_op->mmap and vm_ops->fault aren't enough to identify filesystem.

This prints file name, vm_ops->fault, f_op->mmap and a_ops->readpage (which is almost always implemented and filesystem-specific).

Example:

[   23.676410] BUG: Bad page map in process sh  pte:1b7e6025 pmd:19bbd067
[   23.676887] page:ffffea00006df980 count:4 mapcount:1 mapping:ffff8800196426c0 index:0x97
[   23.677481] flags: 0x10000000000000c(referenced|uptodate)
[   23.677896] page dumped because: bad pte
[   23.678205] addr:00007f52fcb17000 vm_flags:00000075 anon_vma:          (null) mapping:ffff8800196426c0 index:97
[   23.678922] file:libc-2.19.so fault:filemap_fault mmap:generic_file_readonly_mmap readpage:v9fs_vfs_readpage

Signed-off-by Konstantin Khlebnikov <[email protected]>

---
 mm/memory.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

mm/memory.c +6 -6

index 411144f977b1..ea868eea0c88 100644
@@ -690,12 +690,12 @@ static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
 	/*
 	 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
 	 */
-	if (vma->vm_ops)
-		printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n",
-		       vma->vm_ops->fault);
-	if (vma->vm_file)
-		printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n",
-		       vma->vm_file->f_op->mmap);
+	printk(KERN_ALERT
+		"file:%pD fault:%pf mmap:%pf readpage:%pf\n",
+		vma->vm_file,
+		vma->vm_ops ? vma->vm_ops->fault : NULL,
+		vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
+		mapping ? mapping->a_ops->readpage : NULL);
 	dump_stack();
 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 }

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Kirill A. Shutemov

Acked-by on v1 1/1

2015-04-03 17:33 UTC #1 lore raw

Quoted 25 lines · Konstantin Khlebnikov

A lot of filesystems use generic_file_mmap() and filemap_fault(), f_op->mmap and vm_ops->fault aren't enough to identify filesystem.
This prints file name, vm_ops->fault, f_op->mmap and a_ops->readpage (which is almost always implemented and filesystem-specific).
Example:
[   23.676410] BUG: Bad page map in process sh  pte:1b7e6025 pmd:19bbd067
[   23.676887] page:ffffea00006df980 count:4 mapcount:1 mapping:ffff8800196426c0 index:0x97
[   23.677481] flags: 0x10000000000000c(referenced|uptodate)
[   23.677896] page dumped because: bad pte
[   23.678205] addr:00007f52fcb17000 vm_flags:00000075 anon_vma:          (null) mapping:ffff8800196426c0 index:97
[   23.678922] file:libc-2.19.so fault:filemap_fault mmap:generic_file_readonly_mmap readpage:v9fs_vfs_readpage
Signed-off-by Konstantin Khlebnikov <[email protected]>
---
 mm/memory.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)
mm/memory.c +0 -0
index 411144f977b1..ea868eea0c88 100644

mm/memory.c static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr, · line 693

Quoted 10 lines

mm/memory.c +1 -6

@@ -690,12 +690,12 @@ static void print_bad_pte(struct vm_area_struct *vma, unsigned long addr,
 	/*
 	 * Choose text because data symbols depend on CONFIG_KALLSYMS_ALL=y
 	 */
-	if (vma->vm_ops)
-		printk(KERN_ALERT "vma->vm_ops->fault: %pSR\n",
-		       vma->vm_ops->fault);
-	if (vma->vm_file)
-		printk(KERN_ALERT "vma->vm_file->f_op->mmap: %pSR\n",
-		       vma->vm_file->f_op->mmap);
+	printk(KERN_ALERT

pr_alert() ?

Otherwise,

Acked-by Kirill A. Shutemov <[email protected]>

It would be nice to patch dump_vma() to display this information too.

Quoted 14 lines

mm/memory.c +5 -1
+		"file:%pD fault:%pf mmap:%pf readpage:%pf\n",
+		vma->vm_file,
+		vma->vm_ops ? vma->vm_ops->fault : NULL,
+		vma->vm_file ? vma->vm_file->f_op->mmap : NULL,
+		mapping ? mapping->a_ops->readpage : NULL);
 	dump_stack();
 	add_taint(TAINT_BAD_PAGE, LOCKDEP_NOW_UNRELIABLE);
 }
 
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Signature · 7 lines

 Kirill A. Shutemov

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Andrew Morton

maintainer

2015-04-03 22:10 UTC #2 lore raw

In reply to Konstantin Khlebnikov

Quoted 6 lines · On Fri, 03 Apr 2015 20:18:18 +0300 Konstantin Khlebnikov…

A lot of filesystems use generic_file_mmap() and filemap_fault(), f_op->mmap and vm_ops->fault aren't enough to identify filesystem.
This prints file name, vm_ops->fault, f_op->mmap and a_ops->readpage (which is almost always implemented and filesystem-specific).

Quoted 8 lines

Example:

[   23.676410] BUG: Bad page map in process sh  pte:1b7e6025 pmd:19bbd067
[   23.676887] page:ffffea00006df980 count:4 mapcount:1 mapping:ffff8800196426c0 index:0x97
[   23.677481] flags: 0x10000000000000c(referenced|uptodate)
[   23.677896] page dumped because: bad pte
[   23.678205] addr:00007f52fcb17000 vm_flags:00000075 anon_vma:          (null) mapping:ffff8800196426c0 index:97
[   23.678922] file:libc-2.19.so fault:filemap_fault mmap:generic_file_readonly_mmap readpage:v9fs_vfs_readpage

Is that why we print these out? Just to identify the fs type?

There's always vma->vm_file->f_inode->i_sb->s_magic ;)

Konstantin Khlebnikov

2015-04-04 00:47 UTC #3 lore raw

Quoted 17 lines · Andrew Morton

Quoted 6 lines · On Fri, 03 Apr 2015 20:18:18 +0300 Konstantin Khlebnikov…
A lot of filesystems use generic_file_mmap() and filemap_fault(), f_op->mmap and vm_ops->fault aren't enough to identify filesystem.
This prints file name, vm_ops->fault, f_op->mmap and a_ops->readpage (which is almost always implemented and filesystem-specific).
Quoted 8 lines
Example:
[   23.676410] BUG: Bad page map in process sh  pte:1b7e6025 pmd:19bbd067
[   23.676887] page:ffffea00006df980 count:4 mapcount:1 mapping:ffff8800196426c0 index:0x97
[   23.677481] flags: 0x10000000000000c(referenced|uptodate)
[   23.677896] page dumped because: bad pte
[   23.678205] addr:00007f52fcb17000 vm_flags:00000075 anon_vma:          (null) mapping:ffff8800196426c0 index:97
[   23.678922] file:libc-2.19.so fault:filemap_fault mmap:generic_file_readonly_mmap readpage:v9fs_vfs_readpage

Quoted 3 lines

Is that why we print these out? Just to identify the fs type?
There's always vma->vm_file->f_inode->i_sb->s_magic ;)

Yes, but that also might be anon inode/file mapped by some driver, so s_magic isn't enough.

Quoted 7 lines

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Andrew Morton

maintainer

2015-04-04 01:32 UTC #4 lore raw

Quoted 18 lines · On Sat, 4 Apr 2015 03:47:12 +0300 Konstantin Khlebnikov <[email protected]>…

Quoted 17 lines · Andrew Morton
Quoted 14 lines · On Fri, 03 Apr 2015 20:18:18 +0300 Konstantin Khlebnikov…
A lot of filesystems use generic_file_mmap() and filemap_fault(), f_op->mmap and vm_ops->fault aren't enough to identify filesystem.
This prints file name, vm_ops->fault, f_op->mmap and a_ops->readpage (which is almost always implemented and filesystem-specific).
Example:
[   23.676410] BUG: Bad page map in process sh  pte:1b7e6025 pmd:19bbd067
[   23.676887] page:ffffea00006df980 count:4 mapcount:1 mapping:ffff8800196426c0 index:0x97
[   23.677481] flags: 0x10000000000000c(referenced|uptodate)
[   23.677896] page dumped because: bad pte
[   23.678205] addr:00007f52fcb17000 vm_flags:00000075 anon_vma:          (null) mapping:ffff8800196426c0 index:97
[   23.678922] file:libc-2.19.so fault:filemap_fault mmap:generic_file_readonly_mmap readpage:v9fs_vfs_readpage

Quoted 6 lines

Quoted 3 lines
Is that why we print these out? Just to identify the fs type?
There's always vma->vm_file->f_inode->i_sb->s_magic ;)
Yes, but that also might be anon inode/file mapped by some driver, so s_magic isn't enough.

Well, we could ensure that every file_system_type has a valid ->name. Do an audit, put a debug check in register_filesystem()?

Konstantin Khlebnikov

2015-04-04 17:02 UTC #5 lore raw

Quoted 22 lines · Andrew Morton

Quoted 20 lines · On Sat, 4 Apr 2015 03:47:12 +0300 Konstantin Khlebnikov <[email protected]>…
Quoted 19 lines · Andrew Morton
Quoted 6 lines · On Fri, 03 Apr 2015 20:18:18 +0300 Konstantin Khlebnikov…
A lot of filesystems use generic_file_mmap() and filemap_fault(), f_op->mmap and vm_ops->fault aren't enough to identify filesystem.
This prints file name, vm_ops->fault, f_op->mmap and a_ops->readpage (which is almost always implemented and filesystem-specific).
Quoted 8 lines
Example:
[   23.676410] BUG: Bad page map in process sh  pte:1b7e6025 pmd:19bbd067
[   23.676887] page:ffffea00006df980 count:4 mapcount:1 mapping:ffff8800196426c0 index:0x97
[   23.677481] flags: 0x10000000000000c(referenced|uptodate)
[   23.677896] page dumped because: bad pte
[   23.678205] addr:00007f52fcb17000 vm_flags:00000075 anon_vma:          (null) mapping:ffff8800196426c0 index:97
[   23.678922] file:libc-2.19.so fault:filemap_fault mmap:generic_file_readonly_mmap readpage:v9fs_vfs_readpage
Is that why we print these out? Just to identify the fs type?

Quoted 7 lines

Quoted 4 lines
Quoted 1 line
There's always vma->vm_file->f_inode->i_sb->s_magic ;)
Yes, but that also might be anon inode/file mapped by some driver, so s_magic isn't enough.
Well, we could ensure that every file_system_type has a valid ->name. Do an audit, put a debug check in register_filesystem()?

Anyway there are a lot of pseudo filesystems which are a used in many places (bdev sockfs anon_inodefs). Plus char dev inodes belongs to normal filesystem but their f_ops points to somewhere else. Printed mmap/fault/readpage points exactly to the code which is in charge of that page.