Brian Behlendorf cfc9a5c88f Fix zpl_writepage() deadlock ... Disable the normal reclaim path for zpl_putpage(). This ensures that all memory allocations under this call path will never enter direct reclaim. If this were to happen the VM might try to write out additional pages by calling zpl_putpage() again resulting in a deadlock. This sitution is typically handled in Linux by marking each offending allocation GFP_NOFS. However, since much of the code used is common it makes more sense to use PF_MEMALLOC to flag the entire call tree. Alternately, the code could be updated to pass the needed allocation flags but that's a more invasive change. The following example of the above described deadlock was triggered by test 074 in the xfstest suite. Call Trace: [<ffffffff814dcdb2>] down_write+0x32/0x40 [<ffffffffa05af6e4>] dnode_new_blkid+0x94/0x2d0 [zfs] [<ffffffffa0597d66>] dbuf_dirty+0x556/0x750 [zfs] [<ffffffffa05987d1>] dmu_buf_will_dirty+0x81/0xd0 [zfs] [<ffffffffa059ee70>] dmu_write+0x90/0x170 [zfs] [<ffffffffa0611afe>] zfs_putpage+0x2ce/0x360 [zfs] [<ffffffffa062875e>] zpl_putpage+0x1e/0x60 [zfs] [<ffffffffa06287b2>] zpl_writepage+0x12/0x20 [zfs] [<ffffffff8115f907>] writeout+0xa7/0xd0 [<ffffffff8115fa6b>] move_to_new_page+0x13b/0x170 [<ffffffff8115fed4>] migrate_pages+0x434/0x4c0 [<ffffffff811559ab>] compact_zone+0x4fb/0x780 [<ffffffff81155ed1>] compact_zone_order+0xa1/0xe0 [<ffffffff8115602c>] try_to_compact_pages+0x11c/0x190 [<ffffffff811200bb>] __alloc_pages_nodemask+0x5eb/0x8b0 [<ffffffff8115464a>] alloc_pages_current+0xaa/0x110 [<ffffffff8111e36e>] __get_free_pages+0xe/0x50 [<ffffffffa03f0e2f>] kv_alloc+0x3f/0xb0 [spl] [<ffffffffa03f11d9>] spl_kmem_cache_alloc+0x339/0x660 [spl] [<ffffffffa05950b3>] dbuf_create+0x43/0x370 [zfs] [<ffffffffa0596fb1>] __dbuf_hold_impl+0x241/0x480 [zfs] [<ffffffffa0597276>] dbuf_hold_impl+0x86/0xc0 [zfs] [<ffffffffa05977ff>] dbuf_hold_level+0x1f/0x30 [zfs] [<ffffffffa05a9dde>] dmu_tx_check_ioerr+0x4e/0x110 [zfs] [<ffffffffa05aa1f9>] dmu_tx_count_write+0x359/0x6f0 [zfs] [<ffffffffa05aa5df>] dmu_tx_hold_write+0x4f/0x70 [zfs] [<ffffffffa0611a6d>] zfs_putpage+0x23d/0x360 [zfs] [<ffffffffa062875e>] zpl_putpage+0x1e/0x60 [zfs] [<ffffffff811221f9>] write_cache_pages+0x1c9/0x4a0 [<ffffffffa0628738>] zpl_writepages+0x18/0x20 [zfs] [<ffffffff81122521>] do_writepages+0x21/0x40 [<ffffffff8119bbbd>] writeback_single_inode+0xdd/0x2c0 [<ffffffff8119bfbe>] writeback_sb_inodes+0xce/0x180 [<ffffffff8119c11b>] writeback_inodes_wb+0xab/0x1b0 [<ffffffff8119c4bb>] wb_writeback+0x29b/0x3f0 [<ffffffff8119c6cb>] wb_do_writeback+0xbb/0x240 [<ffffffff811308ea>] bdi_forker_task+0x6a/0x310 [<ffffffff8108ddf6>] kthread+0x96/0xa0 Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #327		2011-07-19 16:17:01 -07:00
..
avl	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
nvpair	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
unicode	Support custom build directories and move includes	2010-09-08 12:38:56 -07:00
zcommon	Add "ashift" property to zpool create	2011-06-17 16:35:49 -07:00
zfs	Fix zpl_writepage() deadlock	2011-07-19 16:17:01 -07:00
zpios	Linux 2.6.36 compat, use fops->unlocked_ioctl()	2010-11-10 17:01:08 -08:00
.gitignore	Add .gitignore files to exclude build products	2010-01-08 11:35:17 -08:00
Makefile.in	Fix make distclean for `./configure --with-config=user	2011-04-05 13:33:28 -07:00