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Date: Thu, 01 Feb 2018 16:58:00 -0800
From: syzbot <syzbot+bacbe5d8791f30c9cee5@...kaller.appspotmail.com>
To: akpm@...ux-foundation.org, aneesh.kumar@...ux.vnet.ibm.com,
dan.j.williams@...el.com, james.morse@....com,
kirill.shutemov@...ux.intel.com, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, mingo@...nel.org,
syzkaller-bugs@...glegroups.com, viro@...iv.linux.org.uk
Subject: possible deadlock in get_user_pages_unlocked
Hello,
syzbot hit the following crash on upstream commit
7109a04eae81c41ed529da9f3c48c3655ccea741 (Thu Feb 1 17:37:30 2018 +0000)
Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/ide
So far this crash happened 2 times on upstream.
C reproducer is attached.
syzkaller reproducer is attached.
Raw console output is attached.
compiler: gcc (GCC) 7.1.1 20170620
.config is attached.
IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+bacbe5d8791f30c9cee5@...kaller.appspotmail.com
It will help syzbot understand when the bug is fixed. See footer for
details.
If you forward the report, please keep this part and the footer.
============================================
WARNING: possible recursive locking detected
4.15.0+ #291 Not tainted
--------------------------------------------
syzkaller746568/4446 is trying to acquire lock:
(&mm->mmap_sem){++++}, at: [<000000006212449e>] __get_user_pages_locked
mm/gup.c:909 [inline]
(&mm->mmap_sem){++++}, at: [<000000006212449e>]
get_user_pages_unlocked+0x218/0x4f0 mm/gup.c:990
but task is already holding lock:
(&mm->mmap_sem){++++}, at: [<000000009bfdb3c4>]
get_user_pages_unlocked+0xff/0x4f0 mm/gup.c:989
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&mm->mmap_sem);
lock(&mm->mmap_sem);
*** DEADLOCK ***
May be due to missing lock nesting notation
3 locks held by syzkaller746568/4446:
#0: (&vcpu->mutex){+.+.}, at: [<00000000d22fa6cb>] vcpu_load+0x1c/0x70
arch/x86/kvm/../../../virt/kvm/kvm_main.c:158
#1: (&kvm->srcu){....}, at: [<000000007ac6ea14>] vcpu_enter_guest
arch/x86/kvm/x86.c:7064 [inline]
#1: (&kvm->srcu){....}, at: [<000000007ac6ea14>] vcpu_run
arch/x86/kvm/x86.c:7143 [inline]
#1: (&kvm->srcu){....}, at: [<000000007ac6ea14>]
kvm_arch_vcpu_ioctl_run+0x1b11/0x5bf0 arch/x86/kvm/x86.c:7310
#2: (&mm->mmap_sem){++++}, at: [<000000009bfdb3c4>]
get_user_pages_unlocked+0xff/0x4f0 mm/gup.c:989
stack backtrace:
CPU: 0 PID: 4446 Comm: syzkaller746568 Not tainted 4.15.0+ #291
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x194/0x257 lib/dump_stack.c:53
print_deadlock_bug kernel/locking/lockdep.c:1761 [inline]
check_deadlock kernel/locking/lockdep.c:1805 [inline]
validate_chain kernel/locking/lockdep.c:2401 [inline]
__lock_acquire+0xe8f/0x3e00 kernel/locking/lockdep.c:3431
lock_acquire+0x1d5/0x580 kernel/locking/lockdep.c:3920
down_read+0x96/0x150 kernel/locking/rwsem.c:24
__get_user_pages_locked mm/gup.c:909 [inline]
get_user_pages_unlocked+0x218/0x4f0 mm/gup.c:990
hva_to_pfn_slow arch/x86/kvm/../../../virt/kvm/kvm_main.c:1388 [inline]
hva_to_pfn arch/x86/kvm/../../../virt/kvm/kvm_main.c:1493 [inline]
__gfn_to_pfn_memslot+0x386/0xf80
arch/x86/kvm/../../../virt/kvm/kvm_main.c:1549
try_async_pf+0x13b/0xc40 arch/x86/kvm/mmu.c:3802
tdp_page_fault+0x40a/0xa70 arch/x86/kvm/mmu.c:3898
kvm_mmu_page_fault+0x10d/0x2f0 arch/x86/kvm/mmu.c:4928
handle_ept_violation+0x198/0x550 arch/x86/kvm/vmx.c:6550
vmx_handle_exit+0x25d/0x1ce0 arch/x86/kvm/vmx.c:8893
vcpu_enter_guest arch/x86/kvm/x86.c:7081 [inline]
vcpu_run arch/x86/kvm/x86.c:7143 [inline]
kvm_arch_vcpu_ioctl_run+0x1c69/0x5bf0 arch/x86/kvm/x86.c:7310
kvm_vcpu_ioctl+0x64c/0x1010 arch/x86/kvm/../../../virt/kvm/kvm_main.c:2564
vfs_ioctl fs/ioctl.c:46 [inline]
do_vfs_ioctl+0x1b1/0x1520 fs/ioctl.c:686
SYSC_ioctl fs/ioctl.c:701 [inline]
SyS_ioctl+0x8f/0xc0 fs/ioctl.c:692
entry_SYSCALL_64_fastpath+0x29/0xa0
RIP: 0033:0x448fc9
RSP: 002b:00007ff4b260ada8 EFLAGS: 00000297 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ff4b260b700 RCX: 0000000000448fc9
RDX: 0000000000000000 RSI: 000000000000ae80 RDI: 0000000000000008
RBP: 00007fffca7f9900 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000000
R13: 00007fffca7f985f R14: 00007ff4b260b9c0 R15: 000000000000000d
WARNING: CPU: 0 PID: 4446 at mm/gup.c:498 faultin_page mm/gup.c:498 [inline]
WARNING: CPU: 0 PID: 4446 at mm/gup.c:498 __get_user_pages+0x10a7/0x15f0
mm/gup.c:699
---
This bug is generated by a dumb bot. It may contain errors.
See https://goo.gl/tpsmEJ for details.
Direct all questions to syzkaller@...glegroups.com.
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If you forgot to add the Reported-by tag, once the fix for this bug is
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View attachment "raw.log.txt" of type "text/plain" (16534 bytes)
View attachment "repro.syz.txt" of type "text/plain" (1339 bytes)
View attachment "repro.c.txt" of type "text/plain" (47360 bytes)
View attachment "config.txt" of type "text/plain" (136647 bytes)
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