linux/mm/filemap.c, branch v4.9

mm/filemap: don't allow partially uptodate page for pipes

2016-11-06T18:29:15Z

Starting from 4.9-rc1 kernel, I started noticing some test failures of sendfile(2) and splice(2) (sendfile0N and splice01 from LTP) when testing on sub-page block size filesystems (tested both XFS and ext4), these syscalls start to return EIO in the tests. e.g. sendfile02 1 TFAIL : sendfile02.c:133: sendfile(2) failed to return expected value, expected: 26, got: -1 sendfile02 2 TFAIL : sendfile02.c:133: sendfile(2) failed to return expected value, expected: 24, got: -1 sendfile02 3 TFAIL : sendfile02.c:133: sendfile(2) failed to return expected value, expected: 22, got: -1 sendfile02 4 TFAIL : sendfile02.c:133: sendfile(2) failed to return expected value, expected: 20, got: -1 This is because that in sub-page block size cases, we don't need the whole page to be uptodate, only the part we care about is uptodate is OK (if fs has ->is_partially_uptodate defined). But page_cache_pipe_buf_confirm() doesn't have the ability to check the partially-uptodate case, it needs the whole page to be uptodate. So it returns EIO in this case. This is a regression introduced by commit 82c156f85384 ("switch generic_file_splice_read() to use of ->read_iter()"). Prior to the change, generic_file_splice_read() doesn't allow partially-uptodate page either, so it worked fine. Fix it by skipping the partially-uptodate check if we're working on a pipe in do_generic_file_read(), so we read the whole page from disk as long as the page is not uptodate. Signed-off-by: Eryu Guan Signed-off-by: Al Viro

mm: remove per-zone hashtable of bitlock waitqueues

2016-10-27T16:27:57Z

The per-zone waitqueues exist because of a scalability issue with the page waitqueues on some NUMA machines, but it turns out that they hurt normal loads, and now with the vmalloced stacks they also end up breaking gfs2 that uses a bit_wait on a stack object: wait_on_bit(&gh->gh_iflags, HIF_WAIT, TASK_UNINTERRUPTIBLE) where 'gh' can be a reference to the local variable 'mount_gh' on the stack of fill_super(). The reason the per-zone hash table breaks for this case is that there is no "zone" for virtual allocations, and trying to look up the physical page to get at it will fail (with a BUG_ON()). It turns out that I actually complained to the mm people about the per-zone hash table for another reason just a month ago: the zone lookup also hurts the regular use of "unlock_page()" a lot, because the zone lookup ends up forcing several unnecessary cache misses and generates horrible code. As part of that earlier discussion, we had a much better solution for the NUMA scalability issue - by just making the page lock have a separate contention bit, the waitqueue doesn't even have to be looked at for the normal case. Peter Zijlstra already has a patch for that, but let's see if anybody even notices. In the meantime, let's fix the actual gfs2 breakage by simplifying the bitlock waitqueues and removing the per-zone issue. Reported-by: Andreas Gruenbacher Tested-by: Bob Peterson Acked-by: Mel Gorman Cc: Peter Zijlstra Cc: Andy Lutomirski Cc: Steven Whitehouse Signed-off-by: Linus Torvalds

Merge branch 'work.splice_read' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2016-10-10T20:38:49Z

Pull splice fixups from Al Viro: "A couple of fixups for interaction of pipe-backed iov_iter with O_DIRECT reads + constification of a couple of primitives in uio.h missed by previous rounds. Kudos to davej - his fuzzing has caught those bugs" * 'work.splice_read' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: [btrfs] fix check_direct_IO() for non-iovec iterators constify iov_iter_count() and iter_is_iovec() fix ITER_PIPE interaction with direct_IO

fix ITER_PIPE interaction with direct_IO

2016-10-10T17:36:06Z

by making sure we call iov_iter_advance() on original iov_iter even if direct_IO (done on its copy) has returned 0. It's a no-op for old iov_iter flavours and does the right thing (== truncation of the stuff we'd allocated, but not filled) in ITER_PIPE case. Failures (e.g. -EIO) get caught and dealt with by cleanup in generic_file_read_iter(). Signed-off-by: Al Viro

vfs,mm: fix a dead loop in truncate_inode_pages_range()

2016-10-08T01:46:29Z

We triggered a deadloop in truncate_inode_pages_range() on 32 bits architecture with the test case bellow: ... fd = open(); write(fd, buf, 4096); preadv64(fd, &iovec, 1, 0xffffffff000); ftruncate(fd, 0); ... Then ftruncate() will not return forever. The filesystem used in this case is ubifs, but it can be triggered on many other filesystems. When preadv64() is called with offset=0xffffffff000, a page with index=0xffffffff will be added to the radix tree of ->mapping. Then this page can be found in ->mapping with pagevec_lookup(). After that, truncate_inode_pages_range(), which is called in ftruncate(), will fall into an infinite loop: - find a page with index=0xffffffff, since index>=end, this page won't be truncated - index++, and index become 0 - the page with index=0xffffffff will be found again The data type of index is unsigned long, so index won't overflow to 0 on 64 bits architecture in this case, and the dead loop won't happen. Since truncate_inode_pages_range() is executed with holding lock of inode->i_rwsem, any operation related with this lock will be blocked, and a hung task will happen, e.g.: INFO: task truncate_test:3364 blocked for more than 120 seconds. ... call_rwsem_down_write_failed+0x17/0x30 generic_file_write_iter+0x32/0x1c0 ubifs_write_iter+0xcc/0x170 __vfs_write+0xc4/0x120 vfs_write+0xb2/0x1b0 SyS_write+0x46/0xa0 The page with index=0xffffffff added to ->mapping is useless. Fix this by checking the read position before allocating pages. Link: http://lkml.kernel.org/r/1475151010-40166-1-git-send-email-fangwei1@huawei.com Signed-off-by: Wei Fang Cc: Christoph Hellwig Cc: Dave Chinner Cc: Al Viro Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

do_generic_file_read(): fail immediately if killed

2016-10-08T01:46:27Z

If a fatal signal has been received, fail immediately instead of trying to read more data. If wait_on_page_locked_killable() was interrupted then this page is most likely is not PageUptodate() and in this case do_generic_file_read() will fail after lock_page_killable(). See also commit ebded02788b5 ("mm: filemap: avoid unnecessary calls to lock_page when waiting for IO to complete during a read") [oleg@redhat.com: changelog addition] Link: http://lkml.kernel.org/r/63068e8e-8bee-b208-8441-a3c39a9d9eb6@sandisk.com Signed-off-by: Bart Van Assche Reviewed-by: Jan Kara Acked-by: Oleg Nesterov Acked-by: Michal Hocko Cc: Mel Gorman Cc: Hugh Dickins Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

Merge tag 'xfs-for-linus-4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs

2016-10-06T15:18:10Z

Pull xfs and iomap updates from Dave Chinner: "The main things in this update are the iomap-based DAX infrastructure, an XFS delalloc rework, and a chunk of fixes to how log recovery schedules writeback to prevent spurious corruption detections when recovery of certain items was not required. The other main chunk of code is some preparation for the upcoming reflink functionality. Most of it is generic and cleanups that stand alone, but they were ready and reviewed so are in this pull request. Speaking of reflink, I'm currently planning to send you another pull request next week containing all the new reflink functionality. I'm working through a similar process to the last cycle, where I sent the reverse mapping code in a separate request because of how large it was. The reflink code merge is even bigger than reverse mapping, so I'll be doing the same thing again.... Summary for this update: - change of XFS mailing list to linux-xfs@vger.kernel.org - iomap-based DAX infrastructure w/ XFS and ext2 support - small iomap fixes and additions - more efficient XFS delayed allocation infrastructure based on iomap - a rework of log recovery writeback scheduling to ensure we don't fail recovery when trying to replay items that are already on disk - some preparation patches for upcoming reflink support - configurable error handling fixes and documentation - aio access time update race fixes for XFS and generic_file_read_iter" * tag 'xfs-for-linus-4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/dgc/linux-xfs: (40 commits) fs: update atime before I/O in generic_file_read_iter xfs: update atime before I/O in xfs_file_dio_aio_read ext2: fix possible integer truncation in ext2_iomap_begin xfs: log recovery tracepoints to track current lsn and buffer submission xfs: update metadata LSN in buffers during log recovery xfs: don't warn on buffers not being recovered due to LSN xfs: pass current lsn to log recovery buffer validation xfs: rework log recovery to submit buffers on LSN boundaries xfs: quiesce the filesystem after recovery on readonly mount xfs: remote attribute blocks aren't really userdata ext2: use iomap to implement DAX ext2: stop passing buffer_head to ext2_get_blocks xfs: use iomap to implement DAX xfs: refactor xfs_setfilesize xfs: take the ilock shared if possible in xfs_file_iomap_begin xfs: fix locking for DAX writes dax: provide an iomap based fault handler dax: provide an iomap based dax read/write path dax: don't pass buffer_head to copy_user_dax dax: don't pass buffer_head to dax_insert_mapping ...

mm: filemap: fix mapping->nrpages double accounting in fuse

2016-10-05T16:17:56Z

Commit 22f2ac51b6d6 ("mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page()") switched replace_page_cache() from raw radix tree operations to page_cache_tree_insert() but didn't take into account that the latter function, unlike the raw radix tree op, handles mapping->nrpages. As a result, that counter is bumped for each page replacement rather than balanced out even. The mapping->nrpages counter is used to skip needless radix tree walks when invalidating, truncating, syncing inodes without pages, as well as statistics for userspace. Since the error is positive, we'll do more page cache tree walks than necessary; we won't miss a necessary one. And we'll report more buffer pages to userspace than there are. The error is limited to fuse inodes. Fixes: 22f2ac51b6d6 ("mm: workingset: fix crash in shadow node shrinker caused by replace_page_cache_page()") Signed-off-by: Johannes Weiner Cc: Andrew Morton Cc: Miklos Szeredi Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds

mm: filemap: don't plant shadow entries without radix tree node

2016-10-05T16:17:56Z

When the underflow checks were added to workingset_node_shadow_dec(), they triggered immediately: kernel BUG at ./include/linux/swap.h:276! invalid opcode: 0000 [#1] SMP Modules linked in: isofs usb_storage fuse xt_CHECKSUM ipt_MASQUERADE nf_nat_masquerade_ipv4 tun nf_conntrack_netbios_ns nf_conntrack_broadcast ip6t_REJECT nf_reject_ipv6 soundcore wmi acpi_als pinctrl_sunrisepoint kfifo_buf tpm_tis industrialio acpi_pad pinctrl_intel tpm_tis_core tpm nfsd auth_rpcgss nfs_acl lockd grace sunrpc dm_crypt CPU: 0 PID: 20929 Comm: blkid Not tainted 4.8.0-rc8-00087-gbe67d60ba944 #1 Hardware name: System manufacturer System Product Name/Z170-K, BIOS 1803 05/06/2016 task: ffff8faa93ecd940 task.stack: ffff8faa7f478000 RIP: page_cache_tree_insert+0xf1/0x100 Call Trace: __add_to_page_cache_locked+0x12e/0x270 add_to_page_cache_lru+0x4e/0xe0 mpage_readpages+0x112/0x1d0 blkdev_readpages+0x1d/0x20 __do_page_cache_readahead+0x1ad/0x290 force_page_cache_readahead+0xaa/0x100 page_cache_sync_readahead+0x3f/0x50 generic_file_read_iter+0x5af/0x740 blkdev_read_iter+0x35/0x40 __vfs_read+0xe1/0x130 vfs_read+0x96/0x130 SyS_read+0x55/0xc0 entry_SYSCALL_64_fastpath+0x13/0x8f Code: 03 00 48 8b 5d d8 65 48 33 1c 25 28 00 00 00 44 89 e8 75 19 48 83 c4 18 5b 41 5c 41 5d 41 5e 5d c3 0f 0b 41 bd ef ff ff ff eb d7 <0f> 0b e8 88 68 ef ff 0f 1f 84 00 RIP page_cache_tree_insert+0xf1/0x100 This is a long-standing bug in the way shadow entries are accounted in the radix tree nodes. The shrinker needs to know when radix tree nodes contain only shadow entries, no pages, so node->count is split in half to count shadows in the upper bits and pages in the lower bits. Unfortunately, the radix tree implementation doesn't know of this and assumes all entries are in node->count. When there is a shadow entry directly in root->rnode and the tree is later extended, the radix tree implementation will copy that entry into the new node and and bump its node->count, i.e. increases the page count bits. Once the shadow gets removed and we subtract from the upper counter, node->count underflows and triggers the warning. Afterwards, without node->count reaching 0 again, the radix tree node is leaked. Limit shadow entries to when we have actual radix tree nodes and can count them properly. That means we lose the ability to detect refaults from files that had only the first page faulted in at eviction time. Fixes: 449dd6984d0e ("mm: keep page cache radix tree nodes in check") Signed-off-by: Johannes Weiner Reported-and-tested-by: Linus Torvalds Reviewed-by: Jan Kara Cc: Andrew Morton Cc: stable@vger.kernel.org Signed-off-by: Linus Torvalds

fs: update atime before I/O in generic_file_read_iter

2016-10-02T22:48:08Z

After the call to ->direct_IO the final reference to the file might have been dropped by aio_complete already, and the call to file_accessed might cause a use after free. Instead update the access time before the I/O, similar to how we update the time stamps before writes. Signed-off-by: Christoph Hellwig Reviewed-by: Dave Chinner Signed-off-by: Dave Chinner