From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-la0-f48.google.com (mail-la0-f48.google.com [209.85.215.48]) by kanga.kvack.org (Postfix) with ESMTP id EB47A6B0038 for ; Sat, 4 Apr 2015 13:02:05 -0400 (EDT) Received: by layy10 with SMTP id y10so6647117lay.0 for ; Sat, 04 Apr 2015 10:02:05 -0700 (PDT) Received: from mail-la0-x22d.google.com (mail-la0-x22d.google.com. [2a00:1450:4010:c03::22d]) by mx.google.com with ESMTPS id a2si9363702lah.96.2015.04.04.10.02.03 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sat, 04 Apr 2015 10:02:03 -0700 (PDT) Received: by lagg8 with SMTP id g8so96072819lag.1 for ; Sat, 04 Apr 2015 10:02:03 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <20150403183540.0ed5def0.akpm@linux-foundation.org> References: <20150403171818.22742.92919.stgit@buzz> <20150403151000.b51caa3f692358610fc1ca5d@linux-foundation.org> <20150403183540.0ed5def0.akpm@linux-foundation.org> Date: Sat, 4 Apr 2015 20:02:03 +0300 Message-ID: Subject: Re: [PATCH] mm/memory: print also a_ops->readpage in print_bad_pte From: Konstantin Khlebnikov Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Konstantin Khlebnikov , "linux-mm@kvack.org" , Sasha Levin , Linux Kernel Mailing List On Sat, Apr 4, 2015 at 4:35 AM, Andrew Morton wrote: > On Sat, 4 Apr 2015 03:47:12 +0300 Konstantin Khlebnikov wrote: > >> On Sat, Apr 4, 2015 at 1:10 AM, Andrew Morton wrote: >> > On Fri, 03 Apr 2015 20:18:18 +0300 Konstantin Khlebnikov wrote: >> > >> >> 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 >> > >> > 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()? 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. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org