On 08/11/2014 11:28 PM, Sasha Levin wrote: > On 08/05/2014 09:04 PM, Sasha Levin wrote: >> > Thanks Hugh, Mel. I've added both patches to my local tree and will update tomorrow >> > with the weather. >> > >> > Also: >> > >> > On 08/05/2014 08:42 PM, Hugh Dickins wrote: >>> >> One thing I did wonder, though: at first I was reassured by the >>> >> VM_BUG_ON(!pte_present(pte)) you add to pte_mknuma(); but then thought >>> >> it would be better as VM_BUG_ON(!(val & _PAGE_PRESENT)), being stronger >>> >> - asserting that indeed we do not put NUMA hints on PROT_NONE areas. >>> >> (But I have not tested, perhaps such a VM_BUG_ON would actually fire.) >> > >> > I've added VM_BUG_ON(!(val & _PAGE_PRESENT)) in just as a curiosity, I'll >> > update how that one looks as well. > Sorry for the rather long delay. > > The patch looks fine, the issue didn't reproduce. > > The added VM_BUG_ON didn't trigger either, so maybe we should consider adding > it in. It took a while, but I've managed to hit that VM_BUG_ON: [ 707.975456] kernel BUG at include/asm-generic/pgtable.h:724! [ 707.977147] invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC [ 707.978974] Dumping ftrace buffer: [ 707.980110] (ftrace buffer empty) [ 707.981221] Modules linked in: [ 707.982312] CPU: 18 PID: 9488 Comm: trinity-c538 Not tainted 3.17.0-rc2-next-20140826-sasha-00031-gc48c9ac-dirty #1079 [ 707.982801] task: ffff880165e28000 ti: ffff880165e30000 task.ti: ffff880165e30000 [ 707.982801] RIP: 0010:[<ffffffffb42e3dda>] [<ffffffffb42e3dda>] change_protection_range+0x94a/0x970 [ 707.982801] RSP: 0018:ffff880165e33d98 EFLAGS: 00010246 [ 707.982801] RAX: 000000009d340902 RBX: ffff880511204a08 RCX: 0000000000000100 [ 707.982801] RDX: 000000009d340902 RSI: 0000000041741000 RDI: 000000009d340902 [ 707.982801] RBP: ffff880165e33e88 R08: ffff880708a23c00 R09: 0000000000b52000 [ 707.982801] R10: 0000000000001e01 R11: 0000000000000008 R12: 0000000041751000 [ 707.982801] R13: 00000000000000f7 R14: 000000009d340902 R15: 0000000041741000 [ 707.982801] FS: 00007f358a9aa700(0000) GS:ffff88071c600000(0000) knlGS:0000000000000000 [ 707.982801] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b [ 707.982801] CR2: 00007f3586b69490 CR3: 0000000165d88000 CR4: 00000000000006a0 [ 707.982801] Stack: [ 707.982801] ffff8804db88d058 0000000000000000 ffff88070fb17cf0 0000000000000000 [ 707.982801] ffff880165d88000 0000000000000000 ffff8801686a5000 000000004163e000 [ 707.982801] ffff8801686a5000 0000000000000001 0000000000000025 0000000041750fff [ 707.982801] Call Trace: [ 707.982801] [<ffffffffb42e3e14>] change_protection+0x14/0x30 [ 707.982801] [<ffffffffb42fda3b>] change_prot_numa+0x1b/0x40 [ 707.982801] [<ffffffffb41ad766>] task_numa_work+0x1f6/0x330 [ 707.982801] [<ffffffffb41937c4>] task_work_run+0xc4/0xf0 [ 707.982801] [<ffffffffb40712e7>] do_notify_resume+0x97/0xb0 [ 707.982801] [<ffffffffb74fd6ea>] int_signal+0x12/0x17 [ 707.982801] Code: e8 2c 84 21 03 e9 72 ff ff ff 0f 1f 80 00 00 00 00 0f 0b 48 8b 7d a8 4c 89 f2 4c 89 fe e8 9f 7b 03 00 e9 47 f9 ff ff 0f 0b 0f 0b <0f> 0b 0f 0b 48 8b b5 70 ff ff ff 4c 89 ea 48 89 c7 e8 10 d5 01 [ 707.982801] RIP [<ffffffffb42e3dda>] change_protection_range+0x94a/0x970 [ 707.982801] RSP <ffff880165e33d98> Thanks, Sasha -- 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=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>