On Tue, Dec 17, 2013 at 02:44:17PM +0800, Wanpeng Li wrote: > BUG_ON(!vma) assumption is introduced by commit 0bf598d8 (mbind: add BUG_ON(!vma) > in new_vma_page()), however, even if address = __vma_address(page, vma); and > vma->start < address < vma->end; page_address_in_vma() may still return -EFAULT > because of many other conditions in it. As a result the while loop in new_vma_page() > may end with vma=NULL. This patch revert the commit and also fix the potential > dereference NULL pointer by Dan. http://marc.info/?l=linux-mm&m=137689530323257&w=2 > > kernel BUG at mm/mempolicy.c:1204! > invalid opcode: 0000 [#1] PREEMPT SMP DEBUG_PAGEALLOC > CPU: 3 PID: 7056 Comm: trinity-child3 Not tainted 3.13.0-rc3+ #2 > task: ffff8801ca5295d0 ti: ffff88005ab20000 task.ti: ffff88005ab20000 > RIP: 0010:[<ffffffff8119f200>] [<ffffffff8119f200>] new_vma_page+0x70/0x90 > RSP: 0000:ffff88005ab21db0 EFLAGS: 00010246 > RAX: fffffffffffffff2 RBX: 0000000000000000 RCX: 0000000000000000 > RDX: 0000000008040075 RSI: ffff8801c3d74600 RDI: ffffea00079a8b80 > RBP: ffff88005ab21dc8 R08: 0000000000000004 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: fffffffffffffff2 > R13: ffffea00079a8b80 R14: 0000000000400000 R15: 0000000000400000 > > FS: 00007ff49c6f4740(0000) GS:ffff880244e00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007ff49c68f994 CR3: 000000005a205000 CR4: 00000000001407e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Stack: > ffffea00079a8b80 ffffea00079a8bc0 ffffea00079a8ba0 ffff88005ab21e50 > ffffffff811adc7a 0000000000000000 ffff8801ca5295d0 0000000464e224f8 > 0000000000000000 0000000000000002 0000000000000000 ffff88020ce75c00 > Call Trace: > [<ffffffff811adc7a>] migrate_pages+0x12a/0x850 > [<ffffffff8119f190>] ? alloc_pages_vma+0x1b0/0x1b0 > [<ffffffff8119fa13>] SYSC_mbind+0x513/0x6a0 > [<ffffffff810aa7de>] ? lock_release_holdtime.part.29+0xee/0x170 > [<ffffffff8119fbae>] SyS_mbind+0xe/0x10 > [<ffffffff817626a9>] ia32_do_call+0x13/0x13 > Code: 85 c0 75 2f 4c 89 e1 48 89 da 31 f6 bf da 00 02 00 65 44 8b 04 25 08 f7 1c 00 e8 ec fd ff ff 5b 41 5c 41 5d 5d c3 0f 1f 44 00 00 <0f> 0b 66 0f 1f 44 00 > +00 4c 89 e6 48 89 df ba 01 00 00 00 e8 48 > RIP [<ffffffff8119f200>] new_vma_page+0x70/0x90 > RSP <ffff88005ab21db0> > > Reported-by: Dave Jones <davej@xxxxxxxxxx> > Reported-by: Sasha Levin <sasha.levin@xxxxxxxxxx> > Signed-off-by: Wanpeng Li <liwanp@xxxxxxxxxxxxxxxxxx> Thanks Wanpeng, and everyone! Reviewed-by: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx> > --- > mm/mempolicy.c | 14 ++++++++------ > 1 files changed, 8 insertions(+), 6 deletions(-) > > diff --git a/mm/mempolicy.c b/mm/mempolicy.c > index eca4a31..7247c38 100644 > --- a/mm/mempolicy.c > +++ b/mm/mempolicy.c > @@ -1197,14 +1197,16 @@ static struct page *new_vma_page(struct page *page, unsigned long private, int * > break; > vma = vma->vm_next; > } > + > + if (PageHuge(page)) { > + if (vma) > + return alloc_huge_page_noerr(vma, address, 1); > + else > + return NULL; > + } > /* > - * queue_pages_range() confirms that @page belongs to some vma, > - * so vma shouldn't be NULL. > + * if !vma, alloc_page_vma() will use task or system default policy > */ > - BUG_ON(!vma); > - > - if (PageHuge(page)) > - return alloc_huge_page_noerr(vma, address, 1); > return alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address); > } > #else > -- > 1.7.5.4 > -- 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>