On Thu, 2012-06-28 at 01:02 +0200, Peter Zijlstra wrote: > On Wed, 2012-06-27 at 15:26 -0700, Linus Torvalds wrote: > > On Wed, Jun 27, 2012 at 2:15 PM, Peter Zijlstra <a.p.zijlstra@xxxxxxxxx> wrote: > > > This originated from s390 which does something similar and would allow > > > s390 to use the generic TLB flushing code. > > > > > > The idea is to flush the mm wide cache and tlb a priory and not bother > > > with multiple flushes if the batching isn't large enough. > > > > > > This can be safely done since there cannot be any concurrency on this > > > mm, its either after the process died (exit) or in the middle of > > > execve where the thread switched to the new mm. > > > > I think we actually *used* to do the final TLB flush from within the > > context of the process that died. That doesn't seem to ever be the > > case any more, but it does worry me a bit. Maybe a > > > > VM_BUG_ON(current->active_mm == mm); > > > > or something for the fullmm case? > > OK, added it and am rebooting the test box.. That triggered.. is this a problem though, at this point userspace is very dead so it shouldn't matter, right? Will have to properly think about it tomorrow, its been 1am, brain is mostly sleeping already. ------------[ cut here ]------------ kernel BUG at /home/root/src/linux-2.6/mm/memory.c:221! invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC Modules linked in: CPU 13 Pid: 132, comm: modprobe Not tainted 3.5.0-rc4-01507-g912ca15-dirty #180 Supermicro X8DTN/X8DTN RIP: 0010:[<ffffffff811511bf>] [<ffffffff811511bf>] tlb_gather_mmu+0x9f/0xb0 RSP: 0018:ffff880235b2bd78 EFLAGS: 00010246 RAX: ffff880235b18000 RBX: ffff880235b2bdc0 RCX: ffff880235b18000 RDX: 0000000000000000 RSI: 0000000000000100 RDI: 0000000000000000 RBP: ffff880235b2bd98 R08: 0000000000000018 R09: 0000000000000004 R10: ffffffff81eedfc0 R11: 0000000000000084 R12: ffff8804356b8000 R13: 0000000000000001 R14: ffff880235b185f0 R15: ffff880235b18000 FS: 0000000000000000(0000) GS:ffff880237ce0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000038ce8ae150 CR3: 0000000436ad6000 CR4: 00000000000007e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process modprobe (pid: 132, threadinfo ffff880235b2a000, task ffff880235b18000) Stack: ffff880235b2bd98 0000000000000000 ffff8804356b8000 ffff8804356b8060 ffff880235b2be38 ffffffff8115ad38 ffff880235b2be38 ffff880235b4e000 ffff880235b4e630 ffff8804356b8000 0000000100000000 ffff880235b2bdd8 Call Trace: [<ffffffff8115ad38>] exit_mmap+0x98/0x150 [<ffffffff810bf98e>] ? exit_numa+0xae/0xe0 [<ffffffff81078b74>] mmput+0x84/0x120 [<ffffffff81080ce8>] exit_mm+0x108/0x130 [<ffffffff81081388>] do_exit+0x678/0x950 [<ffffffff811a3ad6>] ? alloc_fd+0xd6/0x120 [<ffffffff811791c0>] ? kmem_cache_free+0x20/0x130 [<ffffffff810819af>] do_group_exit+0x3f/0xa0 [<ffffffff81081a27>] sys_exit_group+0x17/0x20 [<ffffffff81980ed2>] system_call_fastpath+0x16/0x1b Code: 10 74 1a 65 48 8b 04 25 80 ba 00 00 4c 3b a0 90 02 00 00 74 16 4c 89 e7 e8 5f 39 f2 ff 48 8b 5d e8 4c 8b 65 f0 4c 8b 6d f8 c9 c3 <0f> 0b 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 55 48 89 e5 RIP [<ffffffff811511bf>] tlb_gather_mmu+0x9f/0xb0 RSP <ffff880235b2bd78> ---[ end trace f99f121b09c974f8 ]--- -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href