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2015-08-25path_openat(): fix double fput()Al Viro
commit f15133df088ecadd141ea1907f2c96df67c729f0 upstream. path_openat() jumps to the wrong place after do_tmpfile() - it has already done path_cleanup() (as part of path_lookupat() called by do_tmpfile()), so doing that again can lead to double fput(). Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-25signalfd: fix information leak in signalfd_copyinfoAmanieu d'Antras
commit 3ead7c52bdb0ab44f4bb1feed505a8323cc12ba7 upstream. This function may copy the si_addr_lsb field to user mode when it hasn't been initialized, which can leak kernel stack data to user mode. Just checking the value of si_code is insufficient because the same si_code value is shared between multiple signals. This is solved by checking the value of si_signo in addition to si_code. Signed-off-by: Amanieu d'Antras <amanieu@gmail.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-25ocfs2: fix BUG in ocfs2_downconvert_thread_do_work()Joseph Qi
commit 209f7512d007980fd111a74a064d70a3656079cf upstream. The "BUG_ON(list_empty(&osb->blocked_lock_list))" in ocfs2_downconvert_thread_do_work can be triggered in the following case: ocfs2dc has firstly saved osb->blocked_lock_count to local varibale processed, and then processes the dentry lockres. During the dentry put, it calls iput and then deletes rw, inode and open lockres from blocked list in ocfs2_mark_lockres_freeing. And this causes the variable `processed' to not reflect the number of blocked lockres to be processed, which triggers the BUG. Signed-off-by: Joseph Qi <joseph.qi@huawei.com> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-19fsnotify: fix oops in fsnotify_clear_marks_by_group_flags()Jan Kara
commit 8f2f3eb59dff4ec538de55f2e0592fec85966aab upstream. fsnotify_clear_marks_by_group_flags() can race with fsnotify_destroy_marks() so that when fsnotify_destroy_mark_locked() drops mark_mutex, a mark from the list iterated by fsnotify_clear_marks_by_group_flags() can be freed and thus the next entry pointer we have cached may become stale and we dereference free memory. Fix the problem by first moving marks to free to a special private list and then always free the first entry in the special list. This method is safe even when entries from the list can disappear once we drop the lock. Signed-off-by: Jan Kara <jack@suse.com> Reported-by: Ashish Sangwan <a.sangwan@samsung.com> Reviewed-by: Ashish Sangwan <a.sangwan@samsung.com> Cc: Lino Sanfilippo <LinoSanfilippo@gmx.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-19freeing unlinked file indefinitely delayedAl Viro
commit 75a6f82a0d10ef8f13cd8fe7212911a0252ab99e upstream. Normally opening a file, unlinking it and then closing will have the inode freed upon close() (provided that it's not otherwise busy and has no remaining links, of course). However, there's one case where that does *not* happen. Namely, if you open it by fhandle with cold dcache, then unlink() and close(). In normal case you get d_delete() in unlink(2) notice that dentry is busy and unhash it; on the final dput() it will be forcibly evicted from dcache, triggering iput() and inode removal. In this case, though, we end up with *two* dentries - disconnected (created by open-by-fhandle) and regular one (used by unlink()). The latter will have its reference to inode dropped just fine, but the former will not - it's considered hashed (it is on the ->s_anon list), so it will stay around until the memory pressure will finally do it in. As the result, we have the final iput() delayed indefinitely. It's trivial to reproduce - void flush_dcache(void) { system("mount -o remount,rw /"); } static char buf[20 * 1024 * 1024]; main() { int fd; union { struct file_handle f; char buf[MAX_HANDLE_SZ]; } x; int m; x.f.handle_bytes = sizeof(x); chdir("/root"); mkdir("foo", 0700); fd = open("foo/bar", O_CREAT | O_RDWR, 0600); close(fd); name_to_handle_at(AT_FDCWD, "foo/bar", &x.f, &m, 0); flush_dcache(); fd = open_by_handle_at(AT_FDCWD, &x.f, O_RDWR); unlink("foo/bar"); write(fd, buf, sizeof(buf)); system("df ."); /* 20Mb eaten */ close(fd); system("df ."); /* should've freed those 20Mb */ flush_dcache(); system("df ."); /* should be the same as #2 */ } will spit out something like Filesystem 1K-blocks Used Available Use% Mounted on /dev/root 322023 303843 1131 100% / Filesystem 1K-blocks Used Available Use% Mounted on /dev/root 322023 303843 1131 100% / Filesystem 1K-blocks Used Available Use% Mounted on /dev/root 322023 283282 21692 93% / - inode gets freed only when dentry is finally evicted (here we trigger than by remount; normally it would've happened in response to memory pressure hell knows when). Acked-by: J. Bruce Fields <bfields@fieldses.org> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04hpfs: hpfs_error: Remove static buffer, use vsprintf extension %pV insteadJoe Perches
commit a28e4b2b18ccb90df402da3f21e1a83c9d4f8ec1 upstream. Removing unnecessary static buffers is good. Use the vsprintf %pV extension instead. Signed-off-by: Joe Perches <joe@perches.com> Signed-off-by: Mikulas Patocka <mikulas@twibright.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-049p: don't leave a half-initialized inode sitting aroundAl Viro
commit 0a73d0a204a4a04a1e110539c5a524ae51f91d6d upstream. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04fixing infinite OPEN loop in 4.0 stateid recoveryOlga Kornievskaia
commit e8d975e73e5fa05f983fbf2723120edcf68e0b38 upstream. Problem: When an operation like WRITE receives a BAD_STATEID, even though recovery code clears the RECLAIM_NOGRACE recovery flag before recovering the open state, because of clearing delegation state for the associated inode, nfs_inode_find_state_and_recover() gets called and it makes the same state with RECLAIM_NOGRACE flag again. As a results, when we restart looking over the open states, we end up in the infinite loop instead of breaking out in the next test of state flags. Solution: unset the RECLAIM_NOGRACE set because of calling of nfs_inode_find_state_and_recover() after returning from calling recover_open() function. Signed-off-by: Olga Kornievskaia <kolga@netapp.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04NFS: Fix size of NFSACL SETACL operationsChuck Lever
commit d683cc49daf7c5afca8cd9654aaa1bf63cdf2ad9 upstream. When encoding the NFSACL SETACL operation, reserve just the estimated size of the ACL rather than a fixed maximum. This eliminates needless zero padding on the wire that the server ignores. Fixes: ee5dc7732bd5 ('NFS: Fix "kernel BUG at fs/nfs/nfs3xdr.c:1338!"') Signed-off-by: Chuck Lever <chuck.lever@oracle.com> Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04fuse: initialize fc->release before calling itMiklos Szeredi
commit 0ad0b3255a08020eaf50e34ef0d6df5bdf5e09ed upstream. fc->release is called from fuse_conn_put() which was used in the error cleanup before fc->release was initialized. [Jeremiah Mahler <jmmahler@gmail.com>: assign fc->release after calling fuse_conn_init(fc) instead of before.] Signed-off-by: Miklos Szeredi <mszeredi@suse.cz> Fixes: a325f9b92273 ("fuse: update fuse_conn_init() and separate out fuse_conn_kill()") Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04Btrfs: fix memory leak in the extent_same ioctlFilipe Manana
commit 497b4050e0eacd4c746dd396d14916b1e669849d upstream. We were allocating memory with memdup_user() but we were never releasing that memory. This affected pretty much every call to the ioctl, whether it deduplicated extents or not. This issue was reported on IRC by Julian Taylor and on the mailing list by Marcel Ritter, credit goes to them for finding the issue. Reported-by: Julian Taylor <jtaylor.debian@googlemail.com> Reported-by: Marcel Ritter <ritter.marcel@gmail.com> Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: Mark Fasheh <mfasheh@suse.de> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04Btrfs: use kmem_cache_free when freeing entry in inode cacheFilipe Manana
commit c3f4a1685bb87e59c886ee68f7967eae07d4dffa upstream. The free space entries are allocated using kmem_cache_zalloc(), through __btrfs_add_free_space(), therefore we should use kmem_cache_free() and not kfree() to avoid any confusion and any potential problem. Looking at the kfree() definition at mm/slab.c it has the following comment: /* * (...) * * Don't free memory not originally allocated by kmalloc() * or you will run into trouble. */ So better be safe and use kmem_cache_free(). Signed-off-by: Filipe Manana <fdmanana@suse.com> Reviewed-by: David Sterba <dsterba@suse.cz> Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04xfs: fix remote symlinks on V5/CRC filesystemsEric Sandeen
commit 2ac56d3d4bd625450a54d4c3f9292d58f6b88232 upstream. If we create a CRC filesystem, mount it, and create a symlink with a path long enough that it can't live in the inode, we get a very strange result upon remount: # ls -l mnt total 4 lrwxrwxrwx. 1 root root 929 Jun 15 16:58 link -> XSLM XSLM is the V5 symlink block header magic (which happens to be followed by a NUL, so the string looks terminated). xfs_readlink_bmap() advanced cur_chunk by the size of the header for CRC filesystems, but never actually used that pointer; it kept reading from bp->b_addr, which is the start of the block, rather than the start of the symlink data after the header. Looks like this problem goes back to v3.10. Fixing this gets us reading the proper link target, again. Signed-off-by: Eric Sandeen <sandeen@redhat.com> Reviewed-by: Dave Chinner <dchinner@redhat.com> Signed-off-by: Dave Chinner <david@fromorbit.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04jbd2: fix ocfs2 corrupt when updating journal superblock failsJoseph Qi
commit 6f6a6fda294506dfe0e3e0a253bb2d2923f28f0a upstream. If updating journal superblock fails after journal data has been flushed, the error is omitted and this will mislead the caller as a normal case. In ocfs2, the checkpoint will be treated successfully and the other node can get the lock to update. Since the sb_start is still pointing to the old log block, it will rewrite the journal data during journal recovery by the other node. Thus the new updates will be overwritten and ocfs2 corrupts. So in above case we have to return the error, and ocfs2_commit_cache will take care of the error and prevent the other node to do update first. And only after recovering journal it can do the new updates. The issue discussion mail can be found at: https://oss.oracle.com/pipermail/ocfs2-devel/2015-June/010856.html http://comments.gmane.org/gmane.comp.file-systems.ext4/48841 [ Fixed bug in patch which allowed a non-negative error return from jbd2_cleanup_journal_tail() to leak out of jbd2_fjournal_flush(); this was causing xfstests ext4/306 to fail. -- Ted ] Reported-by: Yiwen Jiang <jiangyiwen@huawei.com> Signed-off-by: Joseph Qi <joseph.qi@huawei.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Tested-by: Yiwen Jiang <jiangyiwen@huawei.com> Cc: Junxiao Bi <junxiao.bi@oracle.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04jbd2: use GFP_NOFS in jbd2_cleanup_journal_tail()Dmitry Monakhov
commit b4f1afcd068f6e533230dfed00782cd8a907f96b upstream. jbd2_cleanup_journal_tail() can be invoked by jbd2__journal_start() So allocations should be done with GFP_NOFS [Full stack trace snipped from 3.10-rh7] [<ffffffff815c4bd4>] dump_stack+0x19/0x1b [<ffffffff8105dba1>] warn_slowpath_common+0x61/0x80 [<ffffffff8105dcca>] warn_slowpath_null+0x1a/0x20 [<ffffffff815c2142>] slab_pre_alloc_hook.isra.31.part.32+0x15/0x17 [<ffffffff8119c045>] kmem_cache_alloc+0x55/0x210 [<ffffffff811477f5>] ? mempool_alloc_slab+0x15/0x20 [<ffffffff811477f5>] mempool_alloc_slab+0x15/0x20 [<ffffffff81147939>] mempool_alloc+0x69/0x170 [<ffffffff815cb69e>] ? _raw_spin_unlock_irq+0xe/0x20 [<ffffffff8109160d>] ? finish_task_switch+0x5d/0x150 [<ffffffff811f1a8e>] bio_alloc_bioset+0x1be/0x2e0 [<ffffffff8127ee49>] blkdev_issue_flush+0x99/0x120 [<ffffffffa019a733>] jbd2_cleanup_journal_tail+0x93/0xa0 [jbd2] -->GFP_KERNEL [<ffffffffa019aca1>] jbd2_log_do_checkpoint+0x221/0x4a0 [jbd2] [<ffffffffa019afc7>] __jbd2_log_wait_for_space+0xa7/0x1e0 [jbd2] [<ffffffffa01952d8>] start_this_handle+0x2d8/0x550 [jbd2] [<ffffffff811b02a9>] ? __memcg_kmem_put_cache+0x29/0x30 [<ffffffff8119c120>] ? kmem_cache_alloc+0x130/0x210 [<ffffffffa019573a>] jbd2__journal_start+0xba/0x190 [jbd2] [<ffffffff811532ce>] ? lru_cache_add+0xe/0x10 [<ffffffffa01c9549>] ? ext4_da_write_begin+0xf9/0x330 [ext4] [<ffffffffa01f2c77>] __ext4_journal_start_sb+0x77/0x160 [ext4] [<ffffffffa01c9549>] ext4_da_write_begin+0xf9/0x330 [ext4] [<ffffffff811446ec>] generic_file_buffered_write_iter+0x10c/0x270 [<ffffffff81146918>] __generic_file_write_iter+0x178/0x390 [<ffffffff81146c6b>] __generic_file_aio_write+0x8b/0xb0 [<ffffffff81146ced>] generic_file_aio_write+0x5d/0xc0 [<ffffffffa01bf289>] ext4_file_write+0xa9/0x450 [ext4] [<ffffffff811c31d9>] ? pipe_read+0x379/0x4f0 [<ffffffff811b93f0>] do_sync_write+0x90/0xe0 [<ffffffff811b9b6d>] vfs_write+0xbd/0x1e0 [<ffffffff811ba5b8>] SyS_write+0x58/0xb0 [<ffffffff815d4799>] system_call_fastpath+0x16/0x1b Signed-off-by: Dmitry Monakhov <dmonakhov@openvz.org> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04ext4: replace open coded nofail allocation in ext4_free_blocks()Michal Hocko
commit 7444a072c387a93ebee7066e8aee776954ab0e41 upstream. ext4_free_blocks is looping around the allocation request and mimics __GFP_NOFAIL behavior without any allocation fallback strategy. Let's remove the open coded loop and replace it with __GFP_NOFAIL. Without the flag the allocator has no way to find out never-fail requirement and cannot help in any way. Signed-off-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04ext4: correctly migrate a file with a hole at the beginningEryu Guan
commit 8974fec7d72e3e02752fe0f27b4c3719c78d9a15 upstream. Currently ext4_ind_migrate() doesn't correctly handle a file which contains a hole at the beginning of the file. This caused the migration to be done incorrectly, and then if there is a subsequent following delayed allocation write to the "hole", this would reclaim the same data blocks again and results in fs corruption. # assmuing 4k block size ext4, with delalloc enabled # skip the first block and write to the second block xfs_io -fc "pwrite 4k 4k" -c "fsync" /mnt/ext4/testfile # converting to indirect-mapped file, which would move the data blocks # to the beginning of the file, but extent status cache still marks # that region as a hole chattr -e /mnt/ext4/testfile # delayed allocation writes to the "hole", reclaim the same data block # again, results in i_blocks corruption xfs_io -c "pwrite 0 4k" /mnt/ext4/testfile umount /mnt/ext4 e2fsck -nf /dev/sda6 ... Inode 53, i_blocks is 16, should be 8. Fix? no ... Signed-off-by: Eryu Guan <guaneryu@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04ext4: be more strict when migrating to non-extent based fileEryu Guan
commit d6f123a9297496ad0b6335fe881504c4b5b2a5e5 upstream. Currently the check in ext4_ind_migrate() is not enough before doing the real conversion: a) delayed allocated extents could bypass the check on eh->eh_entries and eh->eh_depth This can be demonstrated by this script xfs_io -fc "pwrite 0 4k" -c "pwrite 8k 4k" /mnt/ext4/testfile chattr -e /mnt/ext4/testfile where testfile has two extents but still be converted to non-extent based file format. b) only extent length is checked but not the offset, which would result in data lose (delalloc) or fs corruption (nodelalloc), because non-extent based file only supports at most (12 + 2^10 + 2^20 + 2^30) blocks This can be demostrated by xfs_io -fc "pwrite 5T 4k" /mnt/ext4/testfile chattr -e /mnt/ext4/testfile sync If delalloc is enabled, dmesg prints EXT4-fs warning (device dm-4): ext4_block_to_path:105: block 1342177280 > max in inode 53 EXT4-fs (dm-4): Delayed block allocation failed for inode 53 at logical offset 1342177280 with max blocks 1 with error 5 EXT4-fs (dm-4): This should not happen!! Data will be lost If delalloc is disabled, e2fsck -nf shows corruption Inode 53, i_size is 5497558142976, should be 4096. Fix? no Fix the two issues by a) forcing all delayed allocation blocks to be allocated before checking eh->eh_depth and eh->eh_entries b) limiting the last logical block of the extent is within direct map Signed-off-by: Eryu Guan <guaneryu@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04ext4: fix reservation release on invalidatepage for delalloc fsLukas Czerner
commit 9705acd63b125dee8b15c705216d7186daea4625 upstream. On delalloc enabled file system on invalidatepage operation in ext4_da_page_release_reservation() we want to clear the delayed buffer and remove the extent covering the delayed buffer from the extent status tree. However currently there is a bug where on the systems with page size > block size we will always remove extents from the start of the page regardless where the actual delayed buffers are positioned in the page. This leads to the errors like this: EXT4-fs warning (device loop0): ext4_da_release_space:1225: ext4_da_release_space: ino 13, to_free 1 with only 0 reserved data blocks This however can cause data loss on writeback time if the file system is in ENOSPC condition because we're releasing reservation for someones else delayed buffer. Fix this by only removing extents that corresponds to the part of the page we want to invalidate. This problem is reproducible by the following fio receipt (however I was only able to reproduce it with fio-2.1 or older. [global] bs=8k iodepth=1024 iodepth_batch=60 randrepeat=1 size=1m directory=/mnt/test numjobs=20 [job1] ioengine=sync bs=1k direct=1 rw=randread filename=file1:file2 [job2] ioengine=libaio rw=randwrite direct=1 filename=file1:file2 [job3] bs=1k ioengine=posixaio rw=randwrite direct=1 filename=file1:file2 [job5] bs=1k ioengine=sync rw=randread filename=file1:file2 [job7] ioengine=libaio rw=randwrite filename=file1:file2 [job8] ioengine=posixaio rw=randwrite filename=file1:file2 [job10] ioengine=mmap rw=randwrite bs=1k filename=file1:file2 [job11] ioengine=mmap rw=randwrite direct=1 filename=file1:file2 Signed-off-by: Lukas Czerner <lczerner@redhat.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04ext4: don't retry file block mapping on bigalloc fs with non-extent fileDarrick J. Wong
commit 292db1bc6c105d86111e858859456bcb11f90f91 upstream. ext4 isn't willing to map clusters to a non-extent file. Don't signal this with an out of space error, since the FS will retry the allocation (which didn't fail) forever. Instead, return EUCLEAN so that the operation will fail immediately all the way back to userspace. (The fix is either to run e2fsck -E bmap2extent, or to chattr +e the file.) Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04ext4: call sync_blockdev() before invalidate_bdev() in put_super()Theodore Ts'o
commit 89d96a6f8e6491f24fc8f99fd6ae66820e85c6c1 upstream. Normally all of the buffers will have been forced out to disk before we call invalidate_bdev(), but there will be some cases, where a file system operation was aborted due to an ext4_error(), where there may still be some dirty buffers in the buffer cache for the device. So try to force them out to memory before calling invalidate_bdev(). This fixes a warning triggered by generic/081: WARNING: CPU: 1 PID: 3473 at /usr/projects/linux/ext4/fs/block_dev.c:56 __blkdev_put+0xb5/0x16f() Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04ext4: fix race between truncate and __ext4_journalled_writepage()Theodore Ts'o
commit bdf96838aea6a265f2ae6cbcfb12a778c84a0b8e upstream. The commit cf108bca465d: "ext4: Invert the locking order of page_lock and transaction start" caused __ext4_journalled_writepage() to drop the page lock before the page was written back, as part of changing the locking order to jbd2_journal_start -> page_lock. However, this introduced a potential race if there was a truncate racing with the data=journalled writeback mode. Fix this by grabbing the page lock after starting the journal handle, and then checking to see if page had gotten truncated out from under us. This fixes a number of different warnings or BUG_ON's when running xfstests generic/086 in data=journalled mode, including: jbd2_journal_dirty_metadata: vdc-8: bad jh for block 115643: transaction (ee3fe7 c0, 164), jh->b_transaction ( (null), 0), jh->b_next_transaction ( (null), 0), jlist 0 - and - kernel BUG at /usr/projects/linux/ext4/fs/jbd2/transaction.c:2200! ... Call Trace: [<c02b2ded>] ? __ext4_journalled_invalidatepage+0x117/0x117 [<c02b2de5>] __ext4_journalled_invalidatepage+0x10f/0x117 [<c02b2ded>] ? __ext4_journalled_invalidatepage+0x117/0x117 [<c027d883>] ? lock_buffer+0x36/0x36 [<c02b2dfa>] ext4_journalled_invalidatepage+0xd/0x22 [<c0229139>] do_invalidatepage+0x22/0x26 [<c0229198>] truncate_inode_page+0x5b/0x85 [<c022934b>] truncate_inode_pages_range+0x156/0x38c [<c0229592>] truncate_inode_pages+0x11/0x15 [<c022962d>] truncate_pagecache+0x55/0x71 [<c02b913b>] ext4_setattr+0x4a9/0x560 [<c01ca542>] ? current_kernel_time+0x10/0x44 [<c026c4d8>] notify_change+0x1c7/0x2be [<c0256a00>] do_truncate+0x65/0x85 [<c0226f31>] ? file_ra_state_init+0x12/0x29 - and - WARNING: CPU: 1 PID: 1331 at /usr/projects/linux/ext4/fs/jbd2/transaction.c:1396 irty_metadata+0x14a/0x1ae() ... Call Trace: [<c01b879f>] ? console_unlock+0x3a1/0x3ce [<c082cbb4>] dump_stack+0x48/0x60 [<c0178b65>] warn_slowpath_common+0x89/0xa0 [<c02ef2cf>] ? jbd2_journal_dirty_metadata+0x14a/0x1ae [<c0178bef>] warn_slowpath_null+0x14/0x18 [<c02ef2cf>] jbd2_journal_dirty_metadata+0x14a/0x1ae [<c02d8615>] __ext4_handle_dirty_metadata+0xd4/0x19d [<c02b2f44>] write_end_fn+0x40/0x53 [<c02b4a16>] ext4_walk_page_buffers+0x4e/0x6a [<c02b59e7>] ext4_writepage+0x354/0x3b8 [<c02b2f04>] ? mpage_release_unused_pages+0xd4/0xd4 [<c02b1b21>] ? wait_on_buffer+0x2c/0x2c [<c02b5a4b>] ? ext4_writepage+0x3b8/0x3b8 [<c02b5a5b>] __writepage+0x10/0x2e [<c0225956>] write_cache_pages+0x22d/0x32c [<c02b5a4b>] ? ext4_writepage+0x3b8/0x3b8 [<c02b6ee8>] ext4_writepages+0x102/0x607 [<c019adfe>] ? sched_clock_local+0x10/0x10e [<c01a8a7c>] ? __lock_is_held+0x2e/0x44 [<c01a8ad5>] ? lock_is_held+0x43/0x51 [<c0226dff>] do_writepages+0x1c/0x29 [<c0276bed>] __writeback_single_inode+0xc3/0x545 [<c0277c07>] writeback_sb_inodes+0x21f/0x36d ... Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-08-04reiserfs: Fix use after free in journal teardownJan Kara
commit 01777836c87081e4f68c4a43c9abe6114805f91e upstream. If do_journal_release() races with do_journal_end() which requeues delayed works for transaction flushing, we can leave work items for flushing outstanding transactions queued while freeing them. That results in use after free and possible crash in run_timers_softirq(). Fix the problem by not requeueing works if superblock is being shut down (MS_ACTIVE not set) and using cancel_delayed_work_sync() in do_journal_release(). Cc: stable@vger.kernel.org Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-07-30vfs: Ignore unlocked mounts in fs_fully_visibleEric W. Biederman
commit ceeb0e5d39fcdf4dca2c997bf225c7fc49200b37 upstream. Limit the mounts fs_fully_visible considers to locked mounts. Unlocked can always be unmounted so considering them adds hassle but no security benefit. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-07-30vfs: Remove incorrect debugging WARN in prepend_pathEric W. Biederman
commit 93e3bce6287e1fb3e60d3324ed08555b5bbafa89 upstream. The warning message in prepend_path is unclear and outdated. It was added as a warning that the mechanism for generating names of pseudo files had been removed from prepend_path and d_dname should be used instead. Unfortunately the warning reads like a general warning, making it unclear what to do with it. Remove the warning. The transition it was added to warn about is long over, and I added code several years ago which in rare cases causes the warning to fire on legitimate code, and the warning is now firing and scaring people for no good reason. Reported-by: Ivan Delalande <colona@arista.com> Reported-by: Omar Sandoval <osandov@osandov.com> Fixes: f48cfddc6729e ("vfs: In d_path don't call d_dname on a mount point") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-07-30fs: Fix S_NOSEC handlingJan Kara
commit 2426f3910069ed47c0cc58559a6d088af7920201 upstream. file_remove_suid() could mistakenly set S_NOSEC inode bit when root was modifying the file. As a result following writes to the file by ordinary user would avoid clearing suid or sgid bits. Fix the bug by checking actual mode bits before setting S_NOSEC. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-07-30get rid of s_files and files_lockAl Viro
commit eee5cc2702929fd41cce28058dc6d6717f723f87 upstream. The only thing we need it for is alt-sysrq-r (emergency remount r/o) and these days we can do just as well without going through the list of files. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jiri Slaby <jslaby@suse.com>
2015-07-30uninline destroy_super(), consolidate alloc_super()Al Viro
commit 7eb5e8826911f2792179f99e77e75fbb7ef53a4a upstream. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jiri Slaby <jslaby@suse.com>
2015-07-30Btrfs: make xattr replace operations atomicFilipe Manana
commit 5f5bc6b1e2d5a6f827bc860ef2dc5b6f365d1339 upstream. Replacing a xattr consists of doing a lookup for its existing value, delete the current value from the respective leaf, release the search path and then finally insert the new value. This leaves a time window where readers (getxattr, listxattrs) won't see any value for the xattr. Xattrs are used to store ACLs, so this has security implications. This change also fixes 2 other existing issues which were: *) Deleting the old xattr value without verifying first if the new xattr will fit in the existing leaf item (in case multiple xattrs are packed in the same item due to name hash collision); *) Returning -EEXIST when the flag XATTR_CREATE is given and the xattr doesn't exist but we have have an existing item that packs muliple xattrs with the same name hash as the input xattr. In this case we should return ENOSPC. A test case for xfstests follows soon. Thanks to Alexandre Oliva for reporting the non-atomicity of the xattr replace implementation. Reported-by: Alexandre Oliva <oliva@gnu.org> Signed-off-by: Filipe Manana <fdmanana@suse.com> Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-07-30pipe: iovec: Fix memory corruption when retrying atomic copy as non-atomicBen Hutchings
pipe_iov_copy_{from,to}_user() may be tried twice with the same iovec, the first time atomically and the second time not. The second attempt needs to continue from the iovec position, pipe buffer offset and remaining length where the first attempt failed, but currently the pipe buffer offset and remaining length are reset. This will corrupt the piped data (possibly also leading to an information leak between processes) and may also corrupt kernel memory. This was fixed upstream by commits f0d1bec9d58d ("new helper: copy_page_from_iter()") and 637b58c2887e ("switch pipe_read() to copy_page_to_iter()"), but those aren't suitable for stable. This fix for older kernel versions was made by Seth Jennings for RHEL and I have extracted it from their update. CVE-2015-1805 References: https://bugzilla.redhat.com/show_bug.cgi?id=1202855 Signed-off-by: Ben Hutchings <ben@decadent.org.uk> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-06-23fs: namespace: suppress 'may be used uninitialized' warningsTim Gardner
commit b8850d1fa8e2f6653e57daf6d08e58c5f5eb2c85 upstream. The gcc version 4.9.1 compiler complains Even though it isn't possible for these variables to not get initialized before they are used. fs/namespace.c: In function ‘SyS_mount’: fs/namespace.c:2720:8: warning: ‘kernel_dev’ may be used uninitialized in this function [-Wmaybe-uninitialized] ret = do_mount(kernel_dev, kernel_dir->name, kernel_type, flags, ^ fs/namespace.c:2699:8: note: ‘kernel_dev’ was declared here char *kernel_dev; ^ fs/namespace.c:2720:8: warning: ‘kernel_type’ may be used uninitialized in this function [-Wmaybe-uninitialized] ret = do_mount(kernel_dev, kernel_dir->name, kernel_type, flags, ^ fs/namespace.c:2697:8: note: ‘kernel_type’ was declared here char *kernel_type; ^ Fix the warnings by simplifying copy_mount_string() as suggested by Al Viro. Cc: Alexander Viro <viro@zeniv.linux.org.uk> Signed-off-by: Tim Gardner <tim.gardner@canonical.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-06-23udf: Check length of extended attributes and allocation descriptorsJan Kara
commit 23b133bdc452aa441fcb9b82cbf6dd05cfd342d0 upstream. Check length of extended attributes and allocation descriptors when loading inodes from disk. Otherwise corrupted filesystems could confuse the code and make the kernel oops. Reported-by: Carl Henrik Lunde <chlunde@ping.uio.no> Cc: stable@vger.kernel.org Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-06-23udf: Remove repeated loads blocksizeJan Kara
commit 79144954278d4bb5989f8b903adcac7a20ff2a5a upstream. Store blocksize in a local variable in udf_fill_inode() since it is used a lot of times. Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-06-23btrfs: cleanup orphans while looking up default subvolumeJeff Mahoney
commit 727b9784b6085c99c2f836bf4fcc2848dc9cf904 upstream. Orphans in the fs tree are cleaned up via open_ctree and subvolume orphans are cleaned via btrfs_lookup_dentry -- except when a default subvolume is in use. The name for the default subvolume uses a manual lookup that doesn't trigger orphan cleanup and needs to trigger it manually as well. This doesn't apply to the remount case since the subvolumes are cleaned up by walking the root radix tree. Signed-off-by: Jeff Mahoney <jeffm@suse.com> Reviewed-by: David Sterba <dsterba@suse.cz> Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-06-23btrfs: incorrect handling for fiemap_fill_next_extent returnChengyu Song
commit 26e726afe01c1c82072cf23a5ed89ce25f39d9f2 upstream. fiemap_fill_next_extent returns 0 on success, -errno on error, 1 if this was the last extent that will fit in user array. If 1 is returned, the return value may eventually returned to user space, which should not happen, according to manpage of ioctl. Signed-off-by: Chengyu Song <csong84@gatech.edu> Reviewed-by: David Sterba <dsterba@suse.cz> Reviewed-by: Liu Bo <bo.li.liu@oracle.com> Signed-off-by: Chris Mason <clm@fb.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-06-03fs/binfmt_elf.c:load_elf_binary(): return -EINVAL on zero-length mappingsAndrew Morton
commit 2b1d3ae940acd11be44c6eced5873d47c2e00ffa upstream. load_elf_binary() returns `retval', not `error'. Fixes: a87938b2e246b81b4fb ("fs/binfmt_elf.c: fix bug in loading of PIE binaries") Reported-by: James Hogan <james.hogan@imgtec.com> Cc: Michael Davidson <md@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-06-03vfs: read file_handle only once in handle_to_pathSasha Levin
commit 161f873b89136eb1e69477c847d5a5033239d9ba upstream. We used to read file_handle twice. Once to get the amount of extra bytes, and once to fetch the entire structure. This may be problematic since we do size verifications only after the first read, so if the number of extra bytes changes in userspace between the first and second calls, we'll have an incoherent view of file_handle. Instead, read the constant size once, and copy that over to the final structure without having to re-read it again. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-06-03jbd2: fix r_count overflows leading to buffer overflow in journal recoveryDarrick J. Wong
commit e531d0bceb402e643a4499de40dd3fa39d8d2e43 upstream. The journal revoke block recovery code does not check r_count for sanity, which means that an evil value of r_count could result in the kernel reading off the end of the revoke table and into whatever garbage lies beyond. This could crash the kernel, so fix that. However, in testing this fix, I discovered that the code to write out the revoke tables also was not correctly checking to see if the block was full -- the current offset check is fine so long as the revoke table space size is a multiple of the record size, but this is not true when either journal_csum_v[23] are set. Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-06-03ext4: check for zero length extent explicitlyEryu Guan
commit 2f974865ffdfe7b9f46a9940836c8b167342563d upstream. The following commit introduced a bug when checking for zero length extent 5946d08 ext4: check for overlapping extents in ext4_valid_extent_entries() Zero length extent could pass the check if lblock is zero. Adding the explicit check for zero length back. Signed-off-by: Eryu Guan <guaneryu@gmail.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-06-03ext4: fix NULL pointer dereference when journal restart failsLukas Czerner
commit 9d506594069355d1fb2de3f9104667312ff08ed3 upstream. Currently when journal restart fails, we'll have the h_transaction of the handle set to NULL to indicate that the handle has been effectively aborted. We handle this situation quietly in the jbd2_journal_stop() and just free the handle and exit because everything else has been done before we attempted (and failed) to restart the journal. Unfortunately there are a number of problems with that approach introduced with commit 41a5b913197c "jbd2: invalidate handle if jbd2_journal_restart() fails" First of all in ext4 jbd2_journal_stop() will be called through __ext4_journal_stop() where we would try to get a hold of the superblock by dereferencing h_transaction which in this case would lead to NULL pointer dereference and crash. In addition we're going to free the handle regardless of the refcount which is bad as well, because others up the call chain will still reference the handle so we might potentially reference already freed memory. Moreover it's expected that we'll get aborted handle as well as detached handle in some of the journalling function as the error propagates up the stack, so it's unnecessary to call WARN_ON every time we get detached handle. And finally we might leak some memory by forgetting to free reserved handle in jbd2_journal_stop() in the case where handle was detached from the transaction (h_transaction is NULL). Fix the NULL pointer dereference in __ext4_journal_stop() by just calling jbd2_journal_stop() quietly as suggested by Jan Kara. Also fix the potential memory leak in jbd2_journal_stop() and use proper handle refcounting before we attempt to free it to avoid use-after-free issues. And finally remove all WARN_ON(!transaction) from the code so that we do not get random traces when something goes wrong because when journal restart fails we will get to some of those functions. Signed-off-by: Lukas Czerner <lczerner@redhat.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu> Reviewed-by: Jan Kara <jack@suse.cz> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-06-03d_walk() might skip too muchAl Viro
commit 2159184ea01e4ae7d15f2017e296d4bc82d5aeb0 upstream. when we find that a child has died while we'd been trying to ascend, we should go into the first live sibling itself, rather than its sibling. Off-by-one in question had been introduced in "deal with deadlock in d_walk()" and the fix needs to be backported to all branches this one has been backported to. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-06-03fs, omfs: add NULL terminator in the end up the token listSasha Levin
commit dcbff39da3d815f08750552fdd04f96b51751129 upstream. match_token() expects a NULL terminator at the end of the token list so that it would know where to stop. Not having one causes it to overrun to invalid memory. In practice, passing a mount option that omfs didn't recognize would sometimes panic the system. Signed-off-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Bob Copeland <me@bobcopeland.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-06-02Fix corrupt SMB2 ioctl requestsSteve French
commit 7ff8d45c9dccf0744404d6fe44468ede7c1b9533 upstream. We were off by one calculating the length of ioctls in some cases because the protocol specification for SMB2 ioctl includes a mininum one byte payload but not all SMB2 ioctl requests actually have a data buffer to send. We were also not zeroing out the return buffer (in case of error this is helpful). Signed-off-by: Steve French <smfrench@gmail.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-05-26mnt: Fail collect_mounts when applied to unmounted mountsEric W. Biederman
commit cd4a40174b71acd021877341684d8bb1dc8ea4ae upstream. The only users of collect_mounts are in audit_tree.c In audit_trim_trees and audit_add_tree_rule the path passed into collect_mounts is generated from kern_path passed an audit_tree pathname which is guaranteed to be an absolute path. In those cases collect_mounts is obviously intended to work on mounted paths and if a race results in paths that are unmounted when collect_mounts it is reasonable to fail early. The paths passed into audit_tag_tree don't have the absolute path check. But are used to play with fsnotify and otherwise interact with the audit_trees, so again operating only on mounted paths appears reasonable. Avoid having to worry about what happens when we try and audit unmounted filesystems by restricting collect_mounts to mounts that appear in the mount tree. Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-05-26aio: fix serial draining in exit_aio()Jens Axboe
commit dc48e56d761610da4ea1088d1bea0a030b8e3e43 upstream. exit_aio() currently serializes killing io contexts. Each context killing ends up having to do percpu_ref_kill(), which in turns has to wait for an RCU grace period. This can take a long time, depending on the number of contexts. And there's no point in doing them serially, when we could be waiting for all of them in one fell swoop. This patches makes my fio thread offload test case exit 0.2s instead of almost 6s. Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Signed-off-by: Jens Axboe <axboe@fb.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-05-26aio: change exit_aio() to load mm->ioctx_table once and avoid rcu_read_lock()Oleg Nesterov
commit 4b70ac5fd9b58bfaa5f25b4ea48f528aefbf3308 upstream. On 04/30, Benjamin LaHaise wrote: > > > - ctx->mmap_size = 0; > > - > > - kill_ioctx(mm, ctx, NULL); > > + if (ctx) { > > + ctx->mmap_size = 0; > > + kill_ioctx(mm, ctx, NULL); > > + } > > Rather than indenting and moving the two lines changing mmap_size and the > kill_ioctx() call, why not just do "if (!ctx) ... continue;"? That reduces > the number of lines changed and avoid excessive indentation. OK. To me the code looks better/simpler with "if (ctx)", but this is subjective of course, I won't argue. The patch still removes the empty line between mmap_size = 0 and kill_ioctx(), we reset mmap_size only for kill_ioctx(). But feel free to remove this change. ------------------------------------------------------------------------------- Subject: [PATCH v3 1/2] aio: change exit_aio() to load mm->ioctx_table once and avoid rcu_read_lock() 1. We can read ->ioctx_table only once and we do not read rcu_read_lock() or even rcu_dereference(). This mm has no users, nobody else can play with ->ioctx_table. Otherwise the code is buggy anyway, if we need rcu_read_lock() in a loop because ->ioctx_table can be updated then kfree(table) is obviously wrong. 2. Update the comment. "exit_mmap(mm) is coming" is the good reason to avoid munmap(), but another reason is that we simply can't do vm_munmap() unless current->mm == mm and this is not true in general, the caller is mmput(). 3. We do not really need to nullify mm->ioctx_table before return, probably the current code does this to catch the potential problems. But in this case RCU_INIT_POINTER(NULL) looks better. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Benjamin LaHaise <bcrl@kvack.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-05-16mnt: Fix fs_fully_visible to verify the root directory is visibleEric W. Biederman
commit 7e96c1b0e0f495c5a7450dc4aa7c9a24ba4305bd upstream. This fixes a dumb bug in fs_fully_visible that allows proc or sys to be mounted if there is a bind mount of part of /proc/ or /sys/ visible. Reported-by: Eric Windisch <ewindisch@docker.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-05-16nilfs2: fix sanity check of btree level in nilfs_btree_root_broken()Ryusuke Konishi
commit d8fd150fe3935e1692bf57c66691e17409ebb9c1 upstream. The range check for b-tree level parameter in nilfs_btree_root_broken() is wrong; it accepts the case of "level == NILFS_BTREE_LEVEL_MAX" even though the level is limited to values in the range of 0 to (NILFS_BTREE_LEVEL_MAX - 1). Since the level parameter is read from storage device and used to index nilfs_btree_path array whose element count is NILFS_BTREE_LEVEL_MAX, it can cause memory overrun during btree operations if the boundary value is set to the level parameter on device. This fixes the broken sanity check and adds a comment to clarify that the upper bound NILFS_BTREE_LEVEL_MAX is exclusive. Signed-off-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-05-16ocfs2: dlm: fix race between purge and get lock resourceJunxiao Bi
commit b1432a2a35565f538586774a03bf277c27fc267d upstream. There is a race window in dlm_get_lock_resource(), which may return a lock resource which has been purged. This will cause the process to hang forever in dlmlock() as the ast msg can't be handled due to its lock resource not existing. dlm_get_lock_resource { ... spin_lock(&dlm->spinlock); tmpres = __dlm_lookup_lockres_full(dlm, lockid, namelen, hash); if (tmpres) { spin_unlock(&dlm->spinlock); >>>>>>>> race window, dlm_run_purge_list() may run and purge the lock resource spin_lock(&tmpres->spinlock); ... spin_unlock(&tmpres->spinlock); } } Signed-off-by: Junxiao Bi <junxiao.bi@oracle.com> Cc: Joseph Qi <joseph.qi@huawei.com> Cc: Mark Fasheh <mfasheh@suse.com> Cc: Joel Becker <jlbec@evilplan.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
2015-05-15fs/seq_file: fallback to vmalloc allocationHeiko Carstens
commit 058504edd02667eef8fac9be27ab3ea74332e9b4 upstream. There are a couple of seq_files which use the single_open() interface. This interface requires that the whole output must fit into a single buffer. E.g. for /proc/stat allocation failures have been observed because an order-4 memory allocation failed due to memory fragmentation. In such situations reading /proc/stat is not possible anymore. Therefore change the seq_file code to fallback to vmalloc allocations which will usually result in a couple of order-0 allocations and hence also work if memory is fragmented. For reference a call trace where reading from /proc/stat failed: sadc: page allocation failure: order:4, mode:0x1040d0 CPU: 1 PID: 192063 Comm: sadc Not tainted 3.10.0-123.el7.s390x #1 [...] Call Trace: show_stack+0x6c/0xe8 warn_alloc_failed+0xd6/0x138 __alloc_pages_nodemask+0x9da/0xb68 __get_free_pages+0x2e/0x58 kmalloc_order_trace+0x44/0xc0 stat_open+0x5a/0xd8 proc_reg_open+0x8a/0x140 do_dentry_open+0x1bc/0x2c8 finish_open+0x46/0x60 do_last+0x382/0x10d0 path_openat+0xc8/0x4f8 do_filp_open+0x46/0xa8 do_sys_open+0x114/0x1f0 sysc_tracego+0x14/0x1a Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Tested-by: David Rientjes <rientjes@google.com> Cc: Ian Kent <raven@themaw.net> Cc: Hendrik Brueckner <brueckner@linux.vnet.ibm.com> Cc: Thorsten Diehl <thorsten.diehl@de.ibm.com> Cc: Andrea Righi <andrea@betterlinux.com> Cc: Christoph Hellwig <hch@infradead.org> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Stefan Bader <stefan.bader@canonical.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jiri Slaby <jslaby@suse.cz>