From: Gavin Shan Date: Thu, 25 Oct 2012 20:38:01 +0000 (-0700) Subject: mm/mmu_notifier: allocate mmu_notifier in advance X-Git-Tag: v3.7-rc3~24^2~6 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=35cfa2b0b491c37e23527822bf365610dbb188e5;p=pandora-kernel.git mm/mmu_notifier: allocate mmu_notifier in advance While allocating mmu_notifier with parameter GFP_KERNEL, swap would start to work in case of tight available memory. Eventually, that would lead to a deadlock while the swap deamon swaps anonymous pages. It was caused by commit e0f3c3f78da29b ("mm/mmu_notifier: init notifier if necessary"). ================================= [ INFO: inconsistent lock state ] 3.7.0-rc1+ #518 Not tainted --------------------------------- inconsistent {RECLAIM_FS-ON-W} -> {IN-RECLAIM_FS-W} usage. kswapd0/35 [HC0[0]:SC0[0]:HE1:SE1] takes: (&mapping->i_mmap_mutex){+.+.?.}, at: page_referenced+0x9c/0x2e0 {RECLAIM_FS-ON-W} state was registered at: mark_held_locks+0x86/0x150 lockdep_trace_alloc+0x67/0xc0 kmem_cache_alloc_trace+0x33/0x230 do_mmu_notifier_register+0x87/0x180 mmu_notifier_register+0x13/0x20 kvm_dev_ioctl+0x428/0x510 do_vfs_ioctl+0x98/0x570 sys_ioctl+0x91/0xb0 system_call_fastpath+0x16/0x1b irq event stamp: 825 hardirqs last enabled at (825): _raw_spin_unlock_irq+0x30/0x60 hardirqs last disabled at (824): _raw_spin_lock_irq+0x19/0x80 softirqs last enabled at (0): copy_process+0x630/0x17c0 softirqs last disabled at (0): (null) ... Simply back out the above commit, which was a small performance optimization. Signed-off-by: Gavin Shan Reported-by: Andrea Righi Tested-by: Andrea Righi Cc: Wanpeng Li Cc: Andrea Arcangeli Cc: Avi Kivity Cc: Hugh Dickins Cc: Marcelo Tosatti Cc: Xiao Guangrong Cc: Sagi Grimberg Cc: Haggai Eran Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-diff-tree failed