* general protection fault in khugepaged @ 2020-07-09 6:43 syzbot 2020-07-17 22:40 ` syzbot 2020-07-18 8:54 ` Hillf Danton 0 siblings, 2 replies; 7+ messages in thread From: syzbot @ 2020-07-09 6:43 UTC (permalink / raw) To: akpm, linux-kernel, linux-mm, netdev, syzkaller-bugs Hello, syzbot found the following crash on: HEAD commit: e44f65fd xen-netfront: remove redundant assignment to vari.. git tree: net-next console output: https://syzkaller.appspot.com/x/log.txt?x=15de54a7100000 kernel config: https://syzkaller.appspot.com/x/.config?x=829871134ca5e230 dashboard link: https://syzkaller.appspot.com/bug?extid=ed318e8b790ca72c5ad0 compiler: gcc (GCC) 10.1.0-syz 20200507 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=113406a7100000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=175597d3100000 IMPORTANT: if you fix the bug, please add the following tag to the commit: Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] CPU: 1 PID: 1155 Comm: khugepaged Not tainted 5.8.0-rc2-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:anon_vma_lock_write include/linux/rmap.h:120 [inline] RIP: 0010:collapse_huge_page mm/khugepaged.c:1110 [inline] RIP: 0010:khugepaged_scan_pmd mm/khugepaged.c:1349 [inline] RIP: 0010:khugepaged_scan_mm_slot mm/khugepaged.c:2110 [inline] RIP: 0010:khugepaged_do_scan mm/khugepaged.c:2193 [inline] RIP: 0010:khugepaged+0x3bba/0x5a10 mm/khugepaged.c:2238 Code: 01 00 00 48 8d bb 88 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 fa 0f 00 00 48 8b 9b 88 00 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 0f 85 d4 0f 00 00 48 8b 3b 48 83 c7 08 e8 9f ff 30 RSP: 0018:ffffc90004be7c80 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81a72d8b RDX: ffff8880a69d8100 RSI: ffffffff81b7606b RDI: ffff88809f0577c0 RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8881ff213a7f R10: 0000000000000080 R11: 0000000000000000 R12: ffffffff8aae6110 R13: ffffc90004be7de0 R14: dffffc0000000000 R15: 0000000020000000 FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000000000000 CR3: 00000001fe0cf000 CR4: 00000000001406e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: kthread+0x3b5/0x4a0 kernel/kthread.c:291 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 Modules linked in: ---[ end trace f1f03dbd2ea0777e ]--- RIP: 0010:anon_vma_lock_write include/linux/rmap.h:120 [inline] RIP: 0010:collapse_huge_page mm/khugepaged.c:1110 [inline] RIP: 0010:khugepaged_scan_pmd mm/khugepaged.c:1349 [inline] RIP: 0010:khugepaged_scan_mm_slot mm/khugepaged.c:2110 [inline] RIP: 0010:khugepaged_do_scan mm/khugepaged.c:2193 [inline] RIP: 0010:khugepaged+0x3bba/0x5a10 mm/khugepaged.c:2238 Code: 01 00 00 48 8d bb 88 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 fa 0f 00 00 48 8b 9b 88 00 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 0f 85 d4 0f 00 00 48 8b 3b 48 83 c7 08 e8 9f ff 30 RSP: 0018:ffffc90004be7c80 EFLAGS: 00010246 RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81a72d8b RDX: ffff8880a69d8100 RSI: ffffffff81b7606b RDI: ffff88809f0577c0 RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8881ff213a7f R10: 0000000000000080 R11: 0000000000000000 R12: ffffffff8aae6110 R13: ffffc90004be7de0 R14: dffffc0000000000 R15: 0000000020000000 FS: 0000000000000000(0000) GS:ffff8880ae600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000004c00c8 CR3: 00000001f7ac5000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 --- This bug is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this bug report. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. syzbot can test patches for this bug, for details see: https://goo.gl/tpsmEJ#testing-patches ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: general protection fault in khugepaged 2020-07-09 6:43 general protection fault in khugepaged syzbot @ 2020-07-17 22:40 ` syzbot 2020-07-17 23:10 ` Kirill A. Shutemov 2020-07-18 8:54 ` Hillf Danton 1 sibling, 1 reply; 7+ messages in thread From: syzbot @ 2020-07-17 22:40 UTC (permalink / raw) To: akpm, kirill.shutemov, linux-kernel, linux-mm, netdev, syzkaller-bugs, torvalds, william.kucharski, yang.shi, ziy syzbot has bisected this issue to: commit ffe945e633b527d5a4577b42cbadec3c7cbcf096 Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Date: Wed Jun 3 23:00:09 2020 +0000 khugepaged: do not stop collapse if less than half PTEs are referenced bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17356c2f100000 start commit: e44f65fd xen-netfront: remove redundant assignment to vari.. git tree: net-next final oops: https://syzkaller.appspot.com/x/report.txt?x=14b56c2f100000 console output: https://syzkaller.appspot.com/x/log.txt?x=10b56c2f100000 kernel config: https://syzkaller.appspot.com/x/.config?x=829871134ca5e230 dashboard link: https://syzkaller.appspot.com/bug?extid=ed318e8b790ca72c5ad0 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=113406a7100000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=175597d3100000 Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com Fixes: ffe945e633b5 ("khugepaged: do not stop collapse if less than half PTEs are referenced") For information about bisection process see: https://goo.gl/tpsmEJ#bisection ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: general protection fault in khugepaged 2020-07-17 22:40 ` syzbot @ 2020-07-17 23:10 ` Kirill A. Shutemov 0 siblings, 0 replies; 7+ messages in thread From: Kirill A. Shutemov @ 2020-07-17 23:10 UTC (permalink / raw) To: syzbot Cc: akpm, kirill.shutemov, linux-kernel, linux-mm, netdev, syzkaller-bugs, torvalds, william.kucharski, yang.shi, ziy On Fri, Jul 17, 2020 at 03:40:04PM -0700, syzbot wrote: > syzbot has bisected this issue to: > > commit ffe945e633b527d5a4577b42cbadec3c7cbcf096 > Author: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> > Date: Wed Jun 3 23:00:09 2020 +0000 > > khugepaged: do not stop collapse if less than half PTEs are referenced > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=17356c2f100000 > start commit: e44f65fd xen-netfront: remove redundant assignment to vari.. > git tree: net-next > final oops: https://syzkaller.appspot.com/x/report.txt?x=14b56c2f100000 > console output: https://syzkaller.appspot.com/x/log.txt?x=10b56c2f100000 > kernel config: https://syzkaller.appspot.com/x/.config?x=829871134ca5e230 > dashboard link: https://syzkaller.appspot.com/bug?extid=ed318e8b790ca72c5ad0 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=113406a7100000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=175597d3100000 > > Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com > Fixes: ffe945e633b5 ("khugepaged: do not stop collapse if less than half PTEs are referenced") > > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > My guess is that anonymous VMA got replaced by file VMA under us. Could you reproduce the issue with the patch below? I have hard time triggering it myself. diff --git a/mm/khugepaged.c b/mm/khugepaged.c index b043c40a21d4..f8ec58a1e72b 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1107,6 +1107,8 @@ static void collapse_huge_page(struct mm_struct *mm, if (mm_find_pmd(mm, address) != pmd) goto out; + if (!vma->anon_vma) + dump_vma(vma); anon_vma_lock_write(vma->anon_vma); mmu_notifier_range_init(&range, MMU_NOTIFY_CLEAR, 0, NULL, mm, -- Kirill A. Shutemov ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: general protection fault in khugepaged 2020-07-09 6:43 general protection fault in khugepaged syzbot 2020-07-17 22:40 ` syzbot @ 2020-07-18 8:54 ` Hillf Danton 2020-07-20 9:08 ` Kirill A. Shutemov 1 sibling, 1 reply; 7+ messages in thread From: Hillf Danton @ 2020-07-18 8:54 UTC (permalink / raw) To: syzbot Cc: linux-kernel, linux-mm, Song Liu, Kirill A . Shutemov, syzkaller-bugs, Markus Elfring, Hillf Danton Wed, 08 Jul 2020 23:43:19 -0700 > syzbot found the following crash on: > > HEAD commit: e44f65fd xen-netfront: remove redundant assignment to vari.. > git tree: net-next > console output: https://syzkaller.appspot.com/x/log.txt?x=15de54a7100000 > kernel config: https://syzkaller.appspot.com/x/.config?x=829871134ca5e230 > dashboard link: https://syzkaller.appspot.com/bug?extid=ed318e8b790ca72c5ad0 > compiler: gcc (GCC) 10.1.0-syz 20200507 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=113406a7100000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=175597d3100000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com > > general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN > KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] > CPU: 1 PID: 1155 Comm: khugepaged Not tainted 5.8.0-rc2-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > RIP: 0010:anon_vma_lock_write include/linux/rmap.h:120 [inline] > RIP: 0010:collapse_huge_page mm/khugepaged.c:1110 [inline] > RIP: 0010:khugepaged_scan_pmd mm/khugepaged.c:1349 [inline] > RIP: 0010:khugepaged_scan_mm_slot mm/khugepaged.c:2110 [inline] > RIP: 0010:khugepaged_do_scan mm/khugepaged.c:2193 [inline] > RIP: 0010:khugepaged+0x3bba/0x5a10 mm/khugepaged.c:2238 > Code: 01 00 00 48 8d bb 88 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 fa 0f 00 00 48 8b 9b 88 00 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 0f 85 d4 0f 00 00 48 8b 3b 48 83 c7 08 e8 9f ff 30 > RSP: 0018:ffffc90004be7c80 EFLAGS: 00010246 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81a72d8b > RDX: ffff8880a69d8100 RSI: ffffffff81b7606b RDI: ffff88809f0577c0 > RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8881ff213a7f > R10: 0000000000000080 R11: 0000000000000000 R12: ffffffff8aae6110 > R13: ffffc90004be7de0 R14: dffffc0000000000 R15: 0000000020000000 > FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 0000000000000000 CR3: 00000001fe0cf000 CR4: 00000000001406e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > kthread+0x3b5/0x4a0 kernel/kthread.c:291 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -435,7 +435,8 @@ static inline int khugepaged_test_exit(s } static bool hugepage_vma_check(struct vm_area_struct *vma, - unsigned long vm_flags) + unsigned long vm_flags, + bool anon) { if ((!(vm_flags & VM_HUGEPAGE) && !khugepaged_always()) || (vm_flags & VM_NOHUGEPAGE) || @@ -446,6 +447,8 @@ static bool hugepage_vma_check(struct vm (IS_ENABLED(CONFIG_READ_ONLY_THP_FOR_FS) && vma->vm_file && (vm_flags & VM_DENYWRITE))) { + if (anon) + return false; return IS_ALIGNED((vma->vm_start >> PAGE_SHIFT) - vma->vm_pgoff, HPAGE_PMD_NR); } @@ -499,7 +502,7 @@ int khugepaged_enter_vma_merge(struct vm * khugepaged does not yet work on special mappings. And * file-private shmem THP is not supported. */ - if (!hugepage_vma_check(vma, vm_flags)) + if (!hugepage_vma_check(vma, vm_flags, false)) return 0; hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; @@ -956,7 +959,7 @@ static int hugepage_vma_revalidate(struc hend = vma->vm_end & HPAGE_PMD_MASK; if (address < hstart || address + HPAGE_PMD_SIZE > hend) return SCAN_ADDRESS_RANGE; - if (!hugepage_vma_check(vma, vma->vm_flags)) + if (!hugepage_vma_check(vma, vma->vm_flags, true)) return SCAN_VMA_CHECK; return 0; } @@ -1426,7 +1429,7 @@ void collapse_pte_mapped_thp(struct mm_s * the valid THP. Add extra VM_HUGEPAGE so hugepage_vma_check() * will not fail the vma for missing VM_HUGEPAGE */ - if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE)) + if (!hugepage_vma_check(vma, vma->vm_flags | VM_HUGEPAGE, false)) return; pmd = mm_find_pmd(mm, haddr); @@ -2071,7 +2074,7 @@ static unsigned int khugepaged_scan_mm_s progress++; break; } - if (!hugepage_vma_check(vma, vma->vm_flags)) { + if (!hugepage_vma_check(vma, vma->vm_flags, false)) { skip: progress++; continue; ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: general protection fault in khugepaged 2020-07-18 8:54 ` Hillf Danton @ 2020-07-20 9:08 ` Kirill A. Shutemov 2020-07-22 23:53 ` Song Liu 0 siblings, 1 reply; 7+ messages in thread From: Kirill A. Shutemov @ 2020-07-20 9:08 UTC (permalink / raw) To: Hillf Danton Cc: syzbot, linux-kernel, linux-mm, Song Liu, Kirill A . Shutemov, syzkaller-bugs, Markus Elfring On Sat, Jul 18, 2020 at 04:54:09PM +0800, Hillf Danton wrote: > > Wed, 08 Jul 2020 23:43:19 -0700 > > syzbot found the following crash on: > > > > HEAD commit: e44f65fd xen-netfront: remove redundant assignment to vari.. > > git tree: net-next > > console output: https://syzkaller.appspot.com/x/log.txt?x=15de54a7100000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=829871134ca5e230 > > dashboard link: https://syzkaller.appspot.com/bug?extid=ed318e8b790ca72c5ad0 > > compiler: gcc (GCC) 10.1.0-syz 20200507 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=113406a7100000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=175597d3100000 > > > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > > Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com > > > > general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN > > KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] > > CPU: 1 PID: 1155 Comm: khugepaged Not tainted 5.8.0-rc2-syzkaller #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > > RIP: 0010:anon_vma_lock_write include/linux/rmap.h:120 [inline] > > RIP: 0010:collapse_huge_page mm/khugepaged.c:1110 [inline] > > RIP: 0010:khugepaged_scan_pmd mm/khugepaged.c:1349 [inline] > > RIP: 0010:khugepaged_scan_mm_slot mm/khugepaged.c:2110 [inline] > > RIP: 0010:khugepaged_do_scan mm/khugepaged.c:2193 [inline] > > RIP: 0010:khugepaged+0x3bba/0x5a10 mm/khugepaged.c:2238 > > Code: 01 00 00 48 8d bb 88 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 fa 0f 00 00 48 8b 9b 88 00 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 0f 85 d4 0f 00 00 48 8b 3b 48 83 c7 08 e8 9f ff 30 > > RSP: 0018:ffffc90004be7c80 EFLAGS: 00010246 > > RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81a72d8b > > RDX: ffff8880a69d8100 RSI: ffffffff81b7606b RDI: ffff88809f0577c0 > > RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8881ff213a7f > > R10: 0000000000000080 R11: 0000000000000000 R12: ffffffff8aae6110 > > R13: ffffc90004be7de0 R14: dffffc0000000000 R15: 0000000020000000 > > FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 0000000000000000 CR3: 00000001fe0cf000 CR4: 00000000001406e0 > > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > Call Trace: > > kthread+0x3b5/0x4a0 kernel/kthread.c:291 > > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 > > Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") It looks sane, but I think it's easier to check in hugepage_vma_revalidate(). Something like this (untested): diff --git a/mm/khugepaged.c b/mm/khugepaged.c index b043c40a21d4..700f5160f3e4 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -958,6 +958,9 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, return SCAN_ADDRESS_RANGE; if (!hugepage_vma_check(vma, vma->vm_flags)) return SCAN_VMA_CHECK; + /* Anon VMA expected */ + if (!vma->anon_vma || vma->vm_ops) + return SCAN_VMA_CHECK; return 0; } -- Kirill A. Shutemov ^ permalink raw reply related [flat|nested] 7+ messages in thread
* Re: general protection fault in khugepaged 2020-07-20 9:08 ` Kirill A. Shutemov @ 2020-07-22 23:53 ` Song Liu 2020-07-24 11:06 ` Kirill A. Shutemov 0 siblings, 1 reply; 7+ messages in thread From: Song Liu @ 2020-07-22 23:53 UTC (permalink / raw) To: Kirill A. Shutemov Cc: Hillf Danton, syzbot, open list, Linux MM, Kirill A . Shutemov, syzkaller-bugs, Markus Elfring > On Jul 20, 2020, at 2:08 AM, Kirill A. Shutemov <kirill@shutemov.name> wrote: > > On Sat, Jul 18, 2020 at 04:54:09PM +0800, Hillf Danton wrote: >> >> Wed, 08 Jul 2020 23:43:19 -0700 >>> syzbot found the following crash on: >>> >>> HEAD commit: e44f65fd xen-netfront: remove redundant assignment to vari.. >>> git tree: net-next >>> console output: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_log.txt-3Fx-3D15de54a7100000&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=6MfBZJE4yUynBic_FV4udh1WdM1wXz8vdcsOfuR23y0&e= >>> kernel config: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_.config-3Fx-3D829871134ca5e230&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=KvhWD3PT9mC8iTIUtQGrMj2UJpBMlsmJOv_wx1kxkQQ&e= >>> dashboard link: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_bug-3Fextid-3Ded318e8b790ca72c5ad0&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=sLoGzpV5UcRyP33XaPaGp_NoxP6VSXh4jttnxne6n6I&e= >>> compiler: gcc (GCC) 10.1.0-syz 20200507 >>> syz repro: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_repro.syz-3Fx-3D113406a7100000&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=HXYlOJ8r_Xv84UDkW6MSoEiG122ATfKJdhQlv3J7mao&e= >>> C reproducer: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_repro.c-3Fx-3D175597d3100000&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=c5Vlm43NNztzFCNb0S6s8IKJuVUtEtm0yWwfV55CeAo&e= >>> >>> IMPORTANT: if you fix the bug, please add the following tag to the commit: >>> Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com >>> >>> general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN >>> KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] >>> CPU: 1 PID: 1155 Comm: khugepaged Not tainted 5.8.0-rc2-syzkaller #0 >>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 >>> RIP: 0010:anon_vma_lock_write include/linux/rmap.h:120 [inline] >>> RIP: 0010:collapse_huge_page mm/khugepaged.c:1110 [inline] >>> RIP: 0010:khugepaged_scan_pmd mm/khugepaged.c:1349 [inline] >>> RIP: 0010:khugepaged_scan_mm_slot mm/khugepaged.c:2110 [inline] >>> RIP: 0010:khugepaged_do_scan mm/khugepaged.c:2193 [inline] >>> RIP: 0010:khugepaged+0x3bba/0x5a10 mm/khugepaged.c:2238 >>> Code: 01 00 00 48 8d bb 88 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 fa 0f 00 00 48 8b 9b 88 00 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 0f 85 d4 0f 00 00 48 8b 3b 48 83 c7 08 e8 9f ff 30 >>> RSP: 0018:ffffc90004be7c80 EFLAGS: 00010246 >>> RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81a72d8b >>> RDX: ffff8880a69d8100 RSI: ffffffff81b7606b RDI: ffff88809f0577c0 >>> RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8881ff213a7f >>> R10: 0000000000000080 R11: 0000000000000000 R12: ffffffff8aae6110 >>> R13: ffffc90004be7de0 R14: dffffc0000000000 R15: 0000000020000000 >>> FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 >>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> CR2: 0000000000000000 CR3: 00000001fe0cf000 CR4: 00000000001406e0 >>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 >>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 >>> Call Trace: >>> kthread+0x3b5/0x4a0 kernel/kthread.c:291 >>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 >> >> Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") > > It looks sane, but I think it's easier to check in > hugepage_vma_revalidate(). Something like this (untested): > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > index b043c40a21d4..700f5160f3e4 100644 > --- a/mm/khugepaged.c > +++ b/mm/khugepaged.c > @@ -958,6 +958,9 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, > return SCAN_ADDRESS_RANGE; > if (!hugepage_vma_check(vma, vma->vm_flags)) > return SCAN_VMA_CHECK; > + /* Anon VMA expected */ > + if (!vma->anon_vma || vma->vm_ops) > + return SCAN_VMA_CHECK; > return 0; > } Maybe move the new check to earlier in the function, say right after we get the vma? Thanks, Song ^ permalink raw reply [flat|nested] 7+ messages in thread
* Re: general protection fault in khugepaged 2020-07-22 23:53 ` Song Liu @ 2020-07-24 11:06 ` Kirill A. Shutemov 0 siblings, 0 replies; 7+ messages in thread From: Kirill A. Shutemov @ 2020-07-24 11:06 UTC (permalink / raw) To: Song Liu Cc: Hillf Danton, syzbot, open list, Linux MM, Kirill A . Shutemov, syzkaller-bugs, Markus Elfring On Wed, Jul 22, 2020 at 11:53:11PM +0000, Song Liu wrote: > > > > On Jul 20, 2020, at 2:08 AM, Kirill A. Shutemov <kirill@shutemov.name> wrote: > > > > On Sat, Jul 18, 2020 at 04:54:09PM +0800, Hillf Danton wrote: > >> > >> Wed, 08 Jul 2020 23:43:19 -0700 > >>> syzbot found the following crash on: > >>> > >>> HEAD commit: e44f65fd xen-netfront: remove redundant assignment to vari.. > >>> git tree: net-next > >>> console output: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_log.txt-3Fx-3D15de54a7100000&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=6MfBZJE4yUynBic_FV4udh1WdM1wXz8vdcsOfuR23y0&e= > >>> kernel config: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_.config-3Fx-3D829871134ca5e230&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=KvhWD3PT9mC8iTIUtQGrMj2UJpBMlsmJOv_wx1kxkQQ&e= > >>> dashboard link: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_bug-3Fextid-3Ded318e8b790ca72c5ad0&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=sLoGzpV5UcRyP33XaPaGp_NoxP6VSXh4jttnxne6n6I&e= > >>> compiler: gcc (GCC) 10.1.0-syz 20200507 > >>> syz repro: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_repro.syz-3Fx-3D113406a7100000&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=HXYlOJ8r_Xv84UDkW6MSoEiG122ATfKJdhQlv3J7mao&e= > >>> C reproducer: https://urldefense.proofpoint.com/v2/url?u=https-3A__syzkaller.appspot.com_x_repro.c-3Fx-3D175597d3100000&d=DwIBAg&c=5VD0RTtNlTh3ycd41b3MUw&r=dR8692q0_uaizy0jkrBJQM5k2hfm4CiFxYT8KaysFrg&m=MQfhDjE9yj2_juw34scN2XTASkKaxHCfKtrY5UlwTx4&s=c5Vlm43NNztzFCNb0S6s8IKJuVUtEtm0yWwfV55CeAo&e= > >>> > >>> IMPORTANT: if you fix the bug, please add the following tag to the commit: > >>> Reported-by: syzbot+ed318e8b790ca72c5ad0@syzkaller.appspotmail.com > >>> > >>> general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN > >>> KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] > >>> CPU: 1 PID: 1155 Comm: khugepaged Not tainted 5.8.0-rc2-syzkaller #0 > >>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > >>> RIP: 0010:anon_vma_lock_write include/linux/rmap.h:120 [inline] > >>> RIP: 0010:collapse_huge_page mm/khugepaged.c:1110 [inline] > >>> RIP: 0010:khugepaged_scan_pmd mm/khugepaged.c:1349 [inline] > >>> RIP: 0010:khugepaged_scan_mm_slot mm/khugepaged.c:2110 [inline] > >>> RIP: 0010:khugepaged_do_scan mm/khugepaged.c:2193 [inline] > >>> RIP: 0010:khugepaged+0x3bba/0x5a10 mm/khugepaged.c:2238 > >>> Code: 01 00 00 48 8d bb 88 00 00 00 48 89 f8 48 c1 e8 03 42 80 3c 30 00 0f 85 fa 0f 00 00 48 8b 9b 88 00 00 00 48 89 d8 48 c1 e8 03 <42> 80 3c 30 00 0f 85 d4 0f 00 00 48 8b 3b 48 83 c7 08 e8 9f ff 30 > >>> RSP: 0018:ffffc90004be7c80 EFLAGS: 00010246 > >>> RAX: 0000000000000000 RBX: 0000000000000000 RCX: ffffffff81a72d8b > >>> RDX: ffff8880a69d8100 RSI: ffffffff81b7606b RDI: ffff88809f0577c0 > >>> RBP: 0000000000000000 R08: 0000000000000000 R09: ffff8881ff213a7f > >>> R10: 0000000000000080 R11: 0000000000000000 R12: ffffffff8aae6110 > >>> R13: ffffc90004be7de0 R14: dffffc0000000000 R15: 0000000020000000 > >>> FS: 0000000000000000(0000) GS:ffff8880ae700000(0000) knlGS:0000000000000000 > >>> CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > >>> CR2: 0000000000000000 CR3: 00000001fe0cf000 CR4: 00000000001406e0 > >>> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > >>> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > >>> Call Trace: > >>> kthread+0x3b5/0x4a0 kernel/kthread.c:291 > >>> ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:293 > >> > >> Fixes: 99cb0dbd47a1 ("mm,thp: add read-only THP support for (non-shmem) FS") > > > > It looks sane, but I think it's easier to check in > > hugepage_vma_revalidate(). Something like this (untested): > > > > diff --git a/mm/khugepaged.c b/mm/khugepaged.c > > index b043c40a21d4..700f5160f3e4 100644 > > --- a/mm/khugepaged.c > > +++ b/mm/khugepaged.c > > @@ -958,6 +958,9 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address, > > return SCAN_ADDRESS_RANGE; > > if (!hugepage_vma_check(vma, vma->vm_flags)) > > return SCAN_VMA_CHECK; > > + /* Anon VMA expected */ > > + if (!vma->anon_vma || vma->vm_ops) > > + return SCAN_VMA_CHECK; > > return 0; > > } > > Maybe move the new check to earlier in the function, say right after > we get the vma? Maybe. But we only protect against the race and it's not going to make a difference for performance. -- Kirill A. Shutemov ^ permalink raw reply [flat|nested] 7+ messages in thread
end of thread, other threads:[~2020-07-24 11:06 UTC | newest] Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2020-07-09 6:43 general protection fault in khugepaged syzbot 2020-07-17 22:40 ` syzbot 2020-07-17 23:10 ` Kirill A. Shutemov 2020-07-18 8:54 ` Hillf Danton 2020-07-20 9:08 ` Kirill A. Shutemov 2020-07-22 23:53 ` Song Liu 2020-07-24 11:06 ` Kirill A. Shutemov
This is a public inbox, see mirroring instructions for how to clone and mirror all data and code used for this inbox; as well as URLs for NNTP newsgroup(s).