From: Theodore Ts'o <tytso@mit.edu>
Subject: Please apply these two patches to the 3.18 stable branch
Date: Tue, 22 Sep 2015 14:06:07 -0400
Message-ID: <20150922180607.GA1948@thunk.org>
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Cc: linux-ext4@vger.kernel.org
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The upstream commits are:

0f2af21aae1197 ext4: allocate entire range in zero range
94426f4b964815 ext4: fix loss of delalloc extent info in ext4_zero_range()

The first patch in particular is needed to address the following failure:

    kernel BUG at /usr/projects/linux/ext4-3.18/fs/ext4/inode.c:1242!
    invalid opcode: 0000 [#1] SMP DEBUG_PAGEALLOC
    CPU: 0 PID: 17896 Comm: xfs_io Not tainted 3.18.21-ext4 #2
    Hardware name: Google Google, BIOS Google 01/01/2011
    task: ffff8802104ec7d0 ti: ffff8801f95bc000 task.ti: ffff8801f95bc000
    RIP: 0010:[<ffffffff81216978>]  [<ffffffff81216978>] ext4_da_invalidatepage+0x61/0x293
    RSP: 0018:ffff8801f95bfcf8  EFLAGS: 00010286
    RAX: 0000000000000400 RBX: ffffea0002bec500 RCX: 0100000000000825
    RDX: 00000000fffffc00 RSI: 0000000000000400 RDI: ffffea0002bec500
    RBP: ffff8800b9ffed78 R08: 0000000000000000 R09: 0000000000000000
    R10: ffff8801f95bfce8 R11: ffff8800b9ee8de0 R12: 0000000000000001
    R13: 00000000fffffc00 R14: 0000000000000400 R15: 0000000000000000
    FS:  00000000009a0880(0063) GS:ffff88021de00000(0000) knlGS:0000000000000000
    CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    CR2: 00007fa6ba80d000 CR3: 0000000210633000 CR4: 00000000001406f0
    Stack:
    0000040000000000 0000000000000002 0000000000000002 ffffffff8114e9f2
    0000000000000000 0000000000000002 ffff8800b9ffed78 0000000000000001
    ffffea0002bec500 0000000000000400 0000000000000000 ffffffff81159a98
    Call Trace:
    [<ffffffff8114e9f2>] ? pagecache_get_page+0x27/0x14e
    [<ffffffff81159a98>] ? truncate_inode_pages_range+0x226/0x427
    [<ffffffff81159572>] ? __pagevec_release+0x23/0x2c
    [<ffffffff8114e21e>] ? filemap_fdatawait_range+0xec/0x105
    [<ffffffff8123bf19>] ? ext4_fallocate+0x27e/0x6d2
    [<ffffffff8118d478>] ? do_fallocate+0x137/0x161
    [<ffffffff8118d4eb>] ? SyS_fallocate+0x49/0x65
    [<ffffffff81661889>] ? system_call_fastpath+0x12/0x17
    Code: 44 89 ea 48 89 df 5b 5d 41 5c 41 5d 41 5e 41 5f e9 3c ec ff ff 8b 44 24 04 44 8d 0c 10 41 81 f9 00 10 00 00 77 05 44 39 ca 76 02 <0f> 0b 48 8b 07 f6 c4 08 75 02 0f 0b 48 8b 47 08 31 d2 31 ed 4c 
    RIP  [<ffffffff81216978>] ext4_da_invalidatepage+0x61/0x293
    RSP <ffff8801f95bfcf8>

.... which can be triggered by calling fallocate with
FALLOC_FL_ZERO_RANGE on a file with in a file system using a 1k
blocksize with an offset of 4300 and a length of 512 bytes.

Many thanks!

					- Ted