On Sat, Apr 4, 2015 at 4:35 AM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > On Sat, 4 Apr 2015 03:47:12 +0300 Konstantin Khlebnikov <koct9i@xxxxxxxxx> wrote: > >> On Sat, Apr 4, 2015 at 1:10 AM, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: >> > On Fri, 03 Apr 2015 20:18:18 +0300 Konstantin Khlebnikov <khlebnikov@xxxxxxxxxxxxxx> 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@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>