[syzbot] [mm?] INFO: rcu detected stall in kcov_ioctl (2)

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 3a7e02c040b1 minmax: avoid overly complicated constant exp..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=132e32bd980000
kernel config: https://syzkaller.appspot.com/x/.config?x=381b8eb3d35e3ad9
dashboard link: https://syzkaller.appspot.com/bug?extid=ff2407cef5068e202465
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/198814da854c/disk-3a7e02c0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/868e99275bc0/vmlinux-3a7e02c0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/ce63033f3708/bzImage-3a7e02c0.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+ff2407...@syzkaller.appspotmail.com

rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P9645/1:b..l P9626/1:b..l
rcu: (detected by 0, t=10502 jiffies, g=53081, q=325 ncpus=2)
task:syz-executor state:R running task stack:27168 pid:9626 tgid:9626 ppid:5216 flags:0x00004002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5188 [inline]
__schedule+0xe37/0x5490 kernel/sched/core.c:6529
preempt_schedule_irq+0x51/0x90 kernel/sched/core.c:6851
irqentry_exit+0x36/0x90 kernel/entry/common.c:354
asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702
RIP: 0010:lock_acquire+0x1f2/0x560 kernel/locking/lockdep.c:5727
Code: c1 05 3a 13 9a 7e 83 f8 01 0f 85 ea 02 00 00 9c 58 f6 c4 02 0f 85 d5 02 00 00 48 85 ed 74 01 fb 48 b8 00 00 00 00 00 fc ff df <48> 01 c3 48 c7 03 00 00 00 00 48 c7 43 08 00 00 00 00 48 8b 84 24
RSP: 0018:ffffc90004647698 EFLAGS: 00000206
RAX: dffffc0000000000 RBX: 1ffff920008c8ed5 RCX: 0000000000000001
RDX: 0000000000000001 RSI: ffffffff8b4cc880 RDI: ffffffff8bb08c00
RBP: 0000000000000200 R08: 0000000000000000 R09: fffffbfff28c4cd8
R10: ffffffff946266c7 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: ffffffff8ddb5220 R15: 0000000000000000
rcu_lock_acquire include/linux/rcupdate.h:326 [inline]
rcu_read_lock include/linux/rcupdate.h:838 [inline]
page_ext_get+0x3a/0x310 mm/page_ext.c:535
__set_page_owner+0x96/0x560 mm/page_owner.c:322
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x2d1/0x350 mm/page_alloc.c:1493
prep_new_page mm/page_alloc.c:1501 [inline]
get_page_from_freelist+0x1351/0x2e50 mm/page_alloc.c:3438
__alloc_pages_noprof+0x22b/0x2460 mm/page_alloc.c:4696
alloc_pages_mpol_noprof+0x275/0x610 mm/mempolicy.c:2263
vm_area_alloc_pages mm/vmalloc.c:3584 [inline]
__vmalloc_area_node mm/vmalloc.c:3660 [inline]
__vmalloc_node_range_noprof+0xa6a/0x1520 mm/vmalloc.c:3841
vmalloc_user_noprof+0x6b/0x90 mm/vmalloc.c:3995
kcov_ioctl+0x4f/0x730 kernel/kcov.c:706
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:907 [inline]
__se_sys_ioctl fs/ioctl.c:893 [inline]
__x64_sys_ioctl+0x193/0x220 fs/ioctl.c:893
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa518d76e9b
RSP: 002b:00007ffd114116d0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 0000000000100000 RCX: 00007fa518d76e9b
RDX: 0000000000100000 RSI: ffffffff80086301 RDI: 00000000000000d7
RBP: 00007fa518f05f40 R08: 00000000000000da R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 0000000000000003 R14: 0000000000000009 R15: 0000000000000009
</TASK>
task:syz-executor state:R running task stack:27088 pid:9645 tgid:9645 ppid:5216 flags:0x00000002
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5188 [inline]
__schedule+0xe37/0x5490 kernel/sched/core.c:6529
preempt_schedule_common+0x44/0xc0 kernel/sched/core.c:6708
preempt_schedule_thunk+0x1a/0x30 arch/x86/entry/thunk.S:12
__raw_spin_unlock include/linux/spinlock_api_smp.h:143 [inline]
_raw_spin_unlock+0x3e/0x50 kernel/locking/spinlock.c:186
spin_unlock include/linux/spinlock.h:391 [inline]
insert_page mm/memory.c:2077 [inline]
vm_insert_page+0x45d/0x6d0 mm/memory.c:2226
kcov_mmap+0xda/0x150 kernel/kcov.c:496
call_mmap include/linux/fs.h:2129 [inline]
mmap_region+0x757/0x2760 mm/mmap.c:2957
do_mmap+0xbfb/0xfb0 mm/mmap.c:1468
vm_mmap_pgoff+0x1ba/0x360 mm/util.c:588
ksys_mmap_pgoff+0x332/0x5d0 mm/mmap.c:1514
__do_sys_mmap arch/x86/kernel/sys_x86_64.c:86 [inline]
__se_sys_mmap arch/x86/kernel/sys_x86_64.c:79 [inline]
__x64_sys_mmap+0x125/0x190 arch/x86/kernel/sys_x86_64.c:79
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xcd/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f7bf4f772d3
RSP: 002b:00007ffc20fff0c8 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f7bf5106018 RCX: 00007f7bf4f772d3
RDX: 0000000000000003 RSI: 0000000000200000 RDI: 00007f7bf4601000
RBP: 00007f7bf4600000 R08: 00000000000000d8 R09: 0000000000000000
R10: 0000000000000011 R11: 0000000000000246 R12: 000000000000000c
R13: 0000000000000003 R14: 0000000000000009 R15: 0000000000000009
</TASK>
rcu: rcu_preempt kthread starved for 10561 jiffies! g53081 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0
rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
rcu: RCU grace-period kthread stack dump:
task:rcu_preempt state:R running task stack:27312 pid:17 tgid:17 ppid:2 flags:0x00004000
Call Trace:
<TASK>
context_switch kernel/sched/core.c:5188 [inline]
__schedule+0xe37/0x5490 kernel/sched/core.c:6529
__schedule_loop kernel/sched/core.c:6606 [inline]
schedule+0xe7/0x350 kernel/sched/core.c:6621
schedule_timeout+0x136/0x2a0 kernel/time/timer.c:2581
rcu_gp_fqs_loop+0x1eb/0xb00 kernel/rcu/tree.c:2034
rcu_gp_kthread+0x271/0x380 kernel/rcu/tree.c:2236
kthread+0x2c1/0x3a0 kernel/kthread.c:389
ret_from_fork+0x45/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>
rcu: Stack dump where RCU GP kthread last ran:
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.10.0-syzkaller-12710-g3a7e02c040b1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 06/27/2024
RIP: 0010:native_irq_disable arch/x86/include/asm/irqflags.h:37 [inline]
RIP: 0010:arch_local_irq_disable arch/x86/include/asm/irqflags.h:92 [inline]
RIP: 0010:acpi_safe_halt+0x1a/0x20 drivers/acpi/processor_idle.c:112
Code: 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 65 48 8b 05 48 69 f2 74 48 8b 00 a8 08 75 0c 66 90 0f 00 2d b8 82 aa 00 fb f4 <fa> c3 cc cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90
RSP: 0018:ffffffff8da07d70 EFLAGS: 00000246
RAX: 0000000000004000 RBX: 0000000000000001 RCX: ffffffff8b115519
RDX: 0000000000000001 RSI: ffff88801a2cb800 RDI: ffff88801a2cb864
RBP: ffff88801a2cb864 R08: 0000000000000001 R09: ffffed1017246fe1
R10: ffff8880b9237f0b R11: 0000000000000000 R12: ffff88801c70a800
R13: ffffffff8e94eac0 R14: 0000000000000000 R15: 0000000000000000
FS: 0000000000000000(0000) GS:ffff8880b9200000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1eebebf378 CR3: 000000006bb72000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<IRQ>
</IRQ>
<TASK>
acpi_idle_enter+0xc5/0x160 drivers/acpi/processor_idle.c:702
cpuidle_enter_state+0x85/0x500 drivers/cpuidle/cpuidle.c:267
cpuidle_enter+0x4e/0xa0 drivers/cpuidle/cpuidle.c:388
cpuidle_idle_call kernel/sched/idle.c:230 [inline]
do_idle+0x313/0x3f0 kernel/sched/idle.c:326
cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:424
rest_init+0x16b/0x2b0 init/main.c:747
start_kernel+0x3df/0x4c0 init/main.c:1103
x86_64_start_reservations+0x18/0x30 arch/x86/kernel/head64.c:507
x86_64_start_kernel+0xb2/0xc0 arch/x86/kernel/head64.c:488
common_startup_64+0x13e/0x148
</TASK>


---
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[Andrew Morton]

On Mon, 29 Jul 2024 08:34:33 -0700 syzbot <syzbot+ff2407...@syzkaller.appspotmail.com> wrote:

> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: 3a7e02c040b1 minmax: avoid overly complicated constant exp..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=132e32bd980000
> kernel config: https://syzkaller.appspot.com/x/.config?x=381b8eb3d35e3ad9
> dashboard link: https://syzkaller.appspot.com/bug?extid=ff2407cef5068e202465
> compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/198814da854c/disk-3a7e02c0.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/868e99275bc0/vmlinux-3a7e02c0.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/ce63033f3708/bzImage-3a7e02c0.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+ff2407...@syzkaller.appspotmail.com

Thanks. Possibly kcov_ioctl(KCOV_INIT_TRACE) was passed a crazily huge
size. Perhaps some more realistic checking should be applied there?

Also, vmalloc() shouldn't be doing this even if asked to allocate a
crazily huge size.

[Uladzislau Rezki]

On Mon, Jul 29, 2024 at 02:31:12PM -0700, Andrew Morton wrote:
> On Mon, 29 Jul 2024 08:34:33 -0700 syzbot <syzbot+ff2407...@syzkaller.appspotmail.com> wrote:
>
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit: 3a7e02c040b1 minmax: avoid overly complicated constant exp..
> > git tree: upstream
> > console output: https://syzkaller.appspot.com/x/log.txt?x=132e32bd980000
> > kernel config: https://syzkaller.appspot.com/x/.config?x=381b8eb3d35e3ad9
> > dashboard link: https://syzkaller.appspot.com/bug?extid=ff2407cef5068e202465
> > compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
> >
> > Unfortunately, I don't have any reproducer for this issue yet.
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/198814da854c/disk-3a7e02c0.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/868e99275bc0/vmlinux-3a7e02c0.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/ce63033f3708/bzImage-3a7e02c0.xz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+ff2407...@syzkaller.appspotmail.com
>
> Thanks. Possibly kcov_ioctl(KCOV_INIT_TRACE) was passed a crazily huge
> size. Perhaps some more realistic checking should be applied there?
>
> Also, vmalloc() shouldn't be doing this even if asked to allocate a
> crazily huge size.
>

<snip>
diff --git a/mm/vmalloc.c b/mm/vmalloc.c
index bc21d821d506..450c6b10a357 100644
--- a/mm/vmalloc.c
+++ b/mm/vmalloc.c
@@ -3783,7 +3783,7 @@ void *__vmalloc_node_range_noprof(unsigned long size, unsigned long align,
if (WARN_ON_ONCE(!size))
return NULL;

- if ((size >> PAGE_SHIFT) > totalram_pages()) {
+ if ((size >> PAGE_SHIFT) > totalram_pages() || size > INT32_MAX) {
warn_alloc(gfp_mask, NULL,
"vmalloc error: size %lu, exceeds total pages",
real_size);
<snip>

We can limit it to ~2GB or add a special threshold which will control
the maximum allocation size.

Any thoughts?

--
Uladzislau Rezki