kernel/linux.git/fs/buffer.c, branch v3.4.105

Fix nasty 32-bit overflow bug in buffer i/o code.

2014-12-01T10:02:37+00:00

commit f2d5a94436cc7cc0221b9a81bba2276a25187dd3 upstream. On 32-bit architectures, the legacy buffer_head functions are not always handling the sector number with the proper 64-bit types, and will thus fail on 4TB+ disks. Any code that uses __getblk() (and thus bread(), breadahead(), sb_bread(), sb_breadahead(), sb_getblk()), and calls it using a 64-bit block on a 32-bit arch (where "long" is 32-bit) causes an inifinite loop in __getblk_slow() with an infinite stream of errors logged to dmesg like this: __find_get_block_slow() failed. block=6740375944, b_blocknr=2445408648 b_state=0x00000020, b_size=512 device sda1 blocksize: 512 Note how in hex block is 0x191C1F988 and b_blocknr is 0x91C1F988 i.e. the top 32-bits are missing (in this case the 0x1 at the top). This is because grow_dev_page() is broken and has a 32-bit overflow due to shifting the page index value (a pgoff_t - which is just 32 bits on 32-bit architectures) left-shifted as the block number. But the top bits to get lost as the pgoff_t is not type cast to sector_t / 64-bit before the shift. This patch fixes this issue by type casting "index" to sector_t before doing the left shift. Note this is not a theoretical bug but has been seen in the field on a 4TiB hard drive with logical sector size 512 bytes. This patch has been verified to fix the infinite loop problem on 3.17-rc5 kernel using a 4TB disk image mounted using "-o loop". Without this patch doing a "find /nt" where /nt is an NTFS volume causes the inifinite loop 100% reproducibly whilst with the patch it works fine as expected. Signed-off-by: Anton Altaparmakov Signed-off-by: Linus Torvalds Signed-off-by: Zefan Li

mm: __set_page_dirty uses spin_lock_irqsave instead of spin_lock_irq

2014-02-20T18:45:32+00:00

commit 227d53b397a32a7614667b3ecaf1d89902fb6c12 upstream. To use spin_{un}lock_irq is dangerous if caller disabled interrupt. During aio buffer migration, we have a possibility to see the following call stack. aio_migratepage [disable interrupt] migrate_page_copy clear_page_dirty_for_io set_page_dirty __set_page_dirty_buffers __set_page_dirty spin_lock_irq This mean, current aio migration is a deadlockable. spin_lock_irqsave is a safer alternative and we should use it. Signed-off-by: KOSAKI Motohiro Reported-by: David Rientjes rientjes@google.com> Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

block: replace __getblk_slow misfix by grow_dev_page fix

2012-09-14T17:00:20+00:00

commit 676ce6d5ca3098339c028d44fe0427d1566a4d2d upstream. Commit 91f68c89d8f3 ("block: fix infinite loop in __getblk_slow") is not good: a successful call to grow_buffers() cannot guarantee that the page won't be reclaimed before the immediate next call to __find_get_block(), which is why there was always a loop there. Yesterday I got "EXT4-fs error (device loop0): __ext4_get_inode_loc:3595: inode #19278: block 664: comm cc1: unable to read itable block" on console, which pointed to this commit. I've been trying to bisect for weeks, why kbuild-on-ext4-on-loop-on-tmpfs sometimes fails from a missing header file, under memory pressure on ppc G5. I've never seen this on x86, and I've never seen it on 3.5-rc7 itself, despite that commit being in there: bisection pointed to an irrelevant pinctrl merge, but hard to tell when failure takes between 18 minutes and 38 hours (but so far it's happened quicker on 3.6-rc2). (I've since found such __ext4_get_inode_loc errors in /var/log/messages from previous weeks: why the message never appeared on console until yesterday morning is a mystery for another day.) Revert 91f68c89d8f3, restoring __getblk_slow() to how it was (plus a checkpatch nitfix). Simplify the interface between grow_buffers() and grow_dev_page(), and avoid the infinite loop beyond end of device by instead checking init_page_buffers()'s end_block there (I presume that's more efficient than a repeated call to blkdev_max_block()), returning -ENXIO to __getblk_slow() in that case. And remove akpm's ten-year-old "__getblk() cannot fail ... weird" comment, but that is worrying: are all users of __getblk() really now prepared for a NULL bh beyond end of device, or will some oops?? Signed-off-by: Hugh Dickins Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman

block: fix infinite loop in __getblk_slow

2012-07-19T15:58:55+00:00

commit 91f68c89d8f35fe98ea04159b9a3b42d0149478f upstream. Commit 080399aaaf35 ("block: don't mark buffers beyond end of disk as mapped") exposed a bug in __getblk_slow that causes mount to hang as it loops infinitely waiting for a buffer that lies beyond the end of the disk to become uptodate. The problem was initially reported by Torsten Hilbrich here: https://lkml.org/lkml/2012/6/18/54 and also reported independently here: http://www.sysresccd.org/forums/viewtopic.php?f=13&t=4511 and then Richard W.M. Jones and Marcos Mello noted a few separate bugzillas also associated with the same issue. This patch has been confirmed to fix: https://bugzilla.redhat.com/show_bug.cgi?id=835019 The main problem is here, in __getblk_slow: for (;;) { struct buffer_head * bh; int ret; bh = __find_get_block(bdev, block, size); if (bh) return bh; ret = grow_buffers(bdev, block, size); if (ret < 0) return NULL; if (ret == 0) free_more_memory(); } __find_get_block does not find the block, since it will not be marked as mapped, and so grow_buffers is called to fill in the buffers for the associated page. I believe the for (;;) loop is there primarily to retry in the case of memory pressure keeping grow_buffers from succeeding. However, we also continue to loop for other cases, like the block lying beond the end of the disk. So, the fix I came up with is to only loop when grow_buffers fails due to memory allocation issues (return value of 0). The attached patch was tested by myself, Torsten, and Rich, and was found to resolve the problem in call cases. Signed-off-by: Jeff Moyer Reported-and-Tested-by: Torsten Hilbrich Tested-by: Richard W.M. Jones Reviewed-by: Josh Boyer [ Jens is on vacation, taking this directly - Linus ] Signed-off-by: Linus Torvalds Signed-off-by: Greg Kroah-Hartman

block: don't mark buffers beyond end of disk as mapped

2012-05-11T14:42:14+00:00

Hi, We have a bug report open where a squashfs image mounted on ppc64 would exhibit errors due to trying to read beyond the end of the disk. It can easily be reproduced by doing the following: [root@ibm-p750e-02-lp3 ~]# ls -l install.img -rw-r--r-- 1 root root 142032896 Apr 30 16:46 install.img [root@ibm-p750e-02-lp3 ~]# mount -o loop ./install.img /mnt/test [root@ibm-p750e-02-lp3 ~]# dd if=/dev/loop0 of=/dev/null dd: reading `/dev/loop0': Input/output error 277376+0 records in 277376+0 records out 142016512 bytes (142 MB) copied, 0.9465 s, 150 MB/s In dmesg, you'll find the following: squashfs: version 4.0 (2009/01/31) Phillip Lougher [ 43.106012] attempt to access beyond end of device [ 43.106029] loop0: rw=0, want=277410, limit=277408 [ 43.106039] Buffer I/O error on device loop0, logical block 138704 [ 43.106053] attempt to access beyond end of device [ 43.106057] loop0: rw=0, want=277412, limit=277408 [ 43.106061] Buffer I/O error on device loop0, logical block 138705 [ 43.106066] attempt to access beyond end of device [ 43.106070] loop0: rw=0, want=277414, limit=277408 [ 43.106073] Buffer I/O error on device loop0, logical block 138706 [ 43.106078] attempt to access beyond end of device [ 43.106081] loop0: rw=0, want=277416, limit=277408 [ 43.106085] Buffer I/O error on device loop0, logical block 138707 [ 43.106089] attempt to access beyond end of device [ 43.106093] loop0: rw=0, want=277418, limit=277408 [ 43.106096] Buffer I/O error on device loop0, logical block 138708 [ 43.106101] attempt to access beyond end of device [ 43.106104] loop0: rw=0, want=277420, limit=277408 [ 43.106108] Buffer I/O error on device loop0, logical block 138709 [ 43.106112] attempt to access beyond end of device [ 43.106116] loop0: rw=0, want=277422, limit=277408 [ 43.106120] Buffer I/O error on device loop0, logical block 138710 [ 43.106124] attempt to access beyond end of device [ 43.106128] loop0: rw=0, want=277424, limit=277408 [ 43.106131] Buffer I/O error on device loop0, logical block 138711 [ 43.106135] attempt to access beyond end of device [ 43.106139] loop0: rw=0, want=277426, limit=277408 [ 43.106143] Buffer I/O error on device loop0, logical block 138712 [ 43.106147] attempt to access beyond end of device [ 43.106151] loop0: rw=0, want=277428, limit=277408 [ 43.106154] Buffer I/O error on device loop0, logical block 138713 [ 43.106158] attempt to access beyond end of device [ 43.106162] loop0: rw=0, want=277430, limit=277408 [ 43.106166] attempt to access beyond end of device [ 43.106169] loop0: rw=0, want=277432, limit=277408 ... [ 43.106307] attempt to access beyond end of device [ 43.106311] loop0: rw=0, want=277470, limit=2774 Squashfs manages to read in the end block(s) of the disk during the mount operation. Then, when dd reads the block device, it leads to block_read_full_page being called with buffers that are beyond end of disk, but are marked as mapped. Thus, it would end up submitting read I/O against them, resulting in the errors mentioned above. I fixed the problem by modifying init_page_buffers to only set the buffer mapped if it fell inside of i_size. Cheers, Jeff Signed-off-by: Jeff Moyer Acked-by: Nick Piggin -- Changes from v1->v2: re-used max_block, as suggested by Nick Piggin. Signed-off-by: Jens Axboe

fs/buffer.c: remove BUG() in possible but rare condition

2012-04-26T04:26:33+00:00

While stressing the kernel with with failing allocations today, I hit the following chain of events: alloc_page_buffers(): bh = alloc_buffer_head(GFP_NOFS); if (!bh) goto no_grow; <= path taken grow_dev_page(): bh = alloc_page_buffers(page, size, 0); if (!bh) goto failed; <= taken, consequence of the above and then the failed path BUG()s the kernel. The failure is inserted a litte bit artificially, but even then, I see no reason why it should be deemed impossible in a real box. Even though this is not a condition that we expect to see around every time, failed allocations are expected to be handled, and BUG() sounds just too much. As a matter of fact, grow_dev_page() can return NULL just fine in other circumstances, so I propose we just remove it, then. Signed-off-by: Glauber Costa Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fs: only send IPI to invalidate LRU BH when needed

2012-03-29T00:14:35+00:00

In several code paths, such as when unmounting a file system (but not only) we send an IPI to ask each cpu to invalidate its local LRU BHs. For multi-cores systems that have many cpus that may not have any LRU BH because they are idle or because they have not performed any file system accesses since last invalidation (e.g. CPU crunching on high perfomance computing nodes that write results to shared memory or only using filesystems that do not use the bh layer.) This can lead to loss of performance each time someone switches the KVM (the virtual keyboard and screen type, not the hypervisor) if it has a USB storage stuck in. This patch attempts to only send an IPI to cpus that have LRU BH. Signed-off-by: Gilad Ben-Yossef Acked-by: Peter Zijlstra Cc: Alexander Viro Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

fs: reduce the use of module.h wherever possible

2012-02-29T00:31:58+00:00

For files only using THIS_MODULE and/or EXPORT_SYMBOL, map them onto including export.h -- or if the file isn't even using those, then just delete the include. Fix up any implicit include dependencies that were being masked by module.h along the way. Signed-off-by: Paul Gortmaker

fs: move code out of buffer.c

2012-01-04T03:54:07+00:00

Move invalidate_bdev, block_sync_page into fs/block_dev.c. Export kill_bdev as well, so brd doesn't have to open code it. Reduce buffer_head.h requirement accordingly. Removed a rather large comment from invalidate_bdev, as it looked a bit obsolete to bother moving. The small comment replacing it says enough. Signed-off-by: Nick Piggin Cc: Al Viro Cc: Christoph Hellwig Signed-off-by: Andrew Morton Signed-off-by: Al Viro

Merge branch 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux

2011-11-07T03:02:23+00:00

* 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux: writeback: Add a 'reason' to wb_writeback_work writeback: send work item to queue_io, move_expired_inodes writeback: trace event balance_dirty_pages writeback: trace event bdi_dirty_ratelimit writeback: fix ppc compile warnings on do_div(long long, unsigned long) writeback: per-bdi background threshold writeback: dirty position control - bdi reserve area writeback: control dirty pause time writeback: limit max dirty pause time writeback: IO-less balance_dirty_pages() writeback: per task dirty rate limit writeback: stabilize bdi->dirty_ratelimit writeback: dirty rate control writeback: add bg_threshold parameter to __bdi_update_bandwidth() writeback: dirty position control writeback: account per-bdi accumulated dirtied pages