linux-kernel - [PATCH] mm/memory: print also a_ops->readpage in print_bad

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Message-ID: <20150403171818.22742.92919.stgit@buzz>
Date:	Fri, 03 Apr 2015 20:18:18 +0300
From:	Konstantin Khlebnikov <khlebnikov@...dex-team.ru>
To:	linux-mm@...ck.org, Andrew Morton <akpm@...ux-foundation.org>
Cc:	Sasha Levin <sasha.levin@...cle.com>, linux-kernel@...r.kernel.org
Subject: [PATCH] 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 <khlebnikov@...dex-team.ru>
---
 mm/memory.c |   12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index 411144f977b1..ea868eea0c88 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -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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