• Andrea Righi's avatar
    mm: prevent divide error for small values of vm_dirty_bytes · 9e4a5bda
    Andrea Righi authored
    Avoid setting less than two pages for vm_dirty_bytes: this is necessary to
    avoid potential division by 0 (like the following) in get_dirty_limits().
    
    [   49.951610] divide error: 0000 [#1] PREEMPT SMP
    [   49.952195] last sysfs file: /sys/devices/pci0000:00/0000:00:01.1/host0/target0:0:0/0:0:0:0/block/sda/uevent
    [   49.952195] CPU 1
    [   49.952195] Modules linked in: pcspkr
    [   49.952195] Pid: 3064, comm: dd Not tainted 2.6.30-rc3 #1
    [   49.952195] RIP: 0010:[<ffffffff802d39a9>]  [<ffffffff802d39a9>] get_dirty_limits+0xe9/0x2c0
    [   49.952195] RSP: 0018:ffff88001de03a98  EFLAGS: 00010202
    [   49.952195] RAX: 00000000000000c0 RBX: ffff88001de03b80 RCX: 28f5c28f5c28f5c3
    [   49.952195] RDX: 0000000000000000 RSI: 00000000000000c0 RDI: 0000000000000000
    [   49.952195] RBP: ffff88001de03ae8 R08: 0000000000000000 R09: 0000000000000000
    [   49.952195] R10: ffff88001ddda9a0 R11: 0000000000000001 R12: 0000000000000001
    [   49.952195] R13: ffff88001fbc8218 R14: ffff88001de03b70 R15: ffff88001de03b78
    [   49.952195] FS:  00007fe9a435b6f0(0000) GS:ffff8800025d9000(0000) knlGS:0000000000000000
    [   49.952195] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
    [   49.952195] CR2: 00007fe9a39ab000 CR3: 000000001de38000 CR4: 00000000000006e0
    [   49.952195] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
    [   49.952195] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
    [   49.952195] Process dd (pid: 3064, threadinfo ffff88001de02000, task ffff88001ddda250)
    [   49.952195] Stack:
    [   49.952195]  ffff88001fa0de00 ffff88001f2dbd70 ffff88001f9fe800 000080b900000000
    [   49.952195]  00000000000000c0 ffff8800027a6100 0000000000000400 ffff88001fbc8218
    [   49.952195]  0000000000000000 0000000000000600 ffff88001de03bb8 ffffffff802d3ed7
    [   49.952195] Call Trace:
    [   49.952195]  [<ffffffff802d3ed7>] balance_dirty_pages_ratelimited_nr+0x1d7/0x3f0
    [   49.952195]  [<ffffffff80368f8e>] ? ext3_writeback_write_end+0x9e/0x120
    [   49.952195]  [<ffffffff802cc7df>] generic_file_buffered_write+0x12f/0x330
    [   49.952195]  [<ffffffff802cce8d>] __generic_file_aio_write_nolock+0x26d/0x460
    [   49.952195]  [<ffffffff802cda32>] ? generic_file_aio_write+0x52/0xd0
    [   49.952195]  [<ffffffff802cda49>] generic_file_aio_write+0x69/0xd0
    [   49.952195]  [<ffffffff80365fa6>] ext3_file_write+0x26/0xc0
    [   49.952195]  [<ffffffff803034d1>] do_sync_write+0xf1/0x140
    [   49.952195]  [<ffffffff80290d1a>] ? get_lock_stats+0x2a/0x60
    [   49.952195]  [<ffffffff80280730>] ? autoremove_wake_function+0x0/0x40
    [   49.952195]  [<ffffffff8030411b>] vfs_write+0xcb/0x190
    [   49.952195]  [<ffffffff803042d0>] sys_write+0x50/0x90
    [   49.952195]  [<ffffffff8022ff6b>] system_call_fastpath+0x16/0x1b
    [   49.952195] Code: 00 00 00 2b 05 09 1c 17 01 48 89 c6 49 0f af f4 48 c1 ee 02 48 89 f0 48 f7 e1 48 89 d6 31 d2 48 c1 ee 02 48 0f af 75 d0 48 89 f0 <48> f7 f7 41 8b 95 ac 01 00 00 48 89 c7 49 0f af d4 48 c1 ea 02
    [   49.952195] RIP  [<ffffffff802d39a9>] get_dirty_limits+0xe9/0x2c0
    [   49.952195]  RSP <ffff88001de03a98>
    [   50.096523] ---[ end trace 008d7aa02f244d7b ]---
    Signed-off-by: default avatarAndrea Righi <righi.andrea@gmail.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: David Rientjes <rientjes@google.com>
    Cc: Dave Chinner <david@fromorbit.com>
    Cc: Christoph Lameter <cl@linux-foundation.org>
    Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
    9e4a5bda
sysctl.c 73.9 KB