Re: [syzbot] upstream boot error: WARNING in __context_tracking_enter
On Mon, Mar 22, 2021 at 6:22 PM Mark Rutland wrote:
>
> Hi Russell,
>
> On Fri, Mar 19, 2021 at 10:10:43AM +, Russell King - ARM Linux admin
> wrote:
> > On Fri, Mar 19, 2021 at 10:54:48AM +0100, Dmitry Vyukov wrote:
> > > .On Fri, Mar 19, 2021 at 10:44 AM syzbot
> > > wrote:
> > > > syzbot found the following issue on:
> > > >
> > > > HEAD commit:8b12a62a Merge tag 'drm-fixes-2021-03-19' of
> > > > git://anongit..
> > > > git tree: upstream
> > > > console output: https://syzkaller.appspot.com/x/log.txt?x=17e815aed0
> > > > kernel config:
> > > > https://syzkaller.appspot.com/x/.config?x=cfeed364fc353c32
> > > > dashboard link:
> > > > https://syzkaller.appspot.com/bug?extid=f09a12b2c77bfbbf51bd
> > > > userspace arch: arm
> > > >
> > > > IMPORTANT: if you fix the issue, please add the following tag to the
> > > > commit:
> > > > Reported-by: syzbot+f09a12b2c77bfbbf5...@syzkaller.appspotmail.com
> > >
> > >
> > > +Mark, arm
> > > It did not get far with CONFIG_CONTEXT_TRACKING_FORCE (kernel doesn't
> > > boot).
> >
> > It seems that the path:
> >
> > context_tracking_user_enter()
> > user_enter()
> > context_tracking_enter()
> > __context_tracking_enter()
> > vtime_user_enter()
> >
> > expects preemption to be disabled. It effectively is, because local
> > interrupts are disabled by context_tracking_enter().
> >
> > However, the requirement for preemption to be disabled is not
> > documented... so shrug. Maybe someone can say what the real requirements
> > are here.
>
> From dealing with this recently on arm64, theis is a bit messy. To
> handle this robustly we need to do a few things in sequence, including
> using the *_irqoff() variants of the context_tracking_user_*()
> functions.
>
> I wrote down the constraints in commit:
>
> 23529049c6842382 ("arm64: entry: fix non-NMI user<->kernel transitions")
>
> For user->kernel transitions, the arch code needs the following sequence
> before invoking arbitrary kernel C code:
>
> lockdep_hardirqs_off(CALLER_ADDR0);
> user_exit_irqoff();
> trace_hardirqs_off_finish();
>
> For kernel->user transitions, the arch code needs the following sequence
> once it will no longer invoke arbitrary kernel C code, just before
> returning to userspace:
>
> trace_hardirqs_on_prepare();
> lockdep_hardirqs_on_prepare(CALLER_ADDR0);
> user_enter_irqoff();
> lockdep_hardirqs_on(CALLER_ADDR0);
Hi Russell,
Does Mark's comment make sense to you?
lockdep_assert_preemption_disabled() also checks "&&
this_cpu_read(hardirqs_enabled)", so is it that we also need hardirq's
disabled around user_enter/exit?
This issue currently prevents ARM boot on syzbot.
Re: [syzbot] upstream boot error: WARNING in __context_tracking_enter
Hi Russell,
On Fri, Mar 19, 2021 at 10:10:43AM +, Russell King - ARM Linux admin wrote:
> On Fri, Mar 19, 2021 at 10:54:48AM +0100, Dmitry Vyukov wrote:
> > .On Fri, Mar 19, 2021 at 10:44 AM syzbot
> > wrote:
> > > syzbot found the following issue on:
> > >
> > > HEAD commit:8b12a62a Merge tag 'drm-fixes-2021-03-19' of
> > > git://anongit..
> > > git tree: upstream
> > > console output: https://syzkaller.appspot.com/x/log.txt?x=17e815aed0
> > > kernel config: https://syzkaller.appspot.com/x/.config?x=cfeed364fc353c32
> > > dashboard link:
> > > https://syzkaller.appspot.com/bug?extid=f09a12b2c77bfbbf51bd
> > > userspace arch: arm
> > >
> > > IMPORTANT: if you fix the issue, please add the following tag to the
> > > commit:
> > > Reported-by: syzbot+f09a12b2c77bfbbf5...@syzkaller.appspotmail.com
> >
> >
> > +Mark, arm
> > It did not get far with CONFIG_CONTEXT_TRACKING_FORCE (kernel doesn't boot).
>
> It seems that the path:
>
> context_tracking_user_enter()
> user_enter()
> context_tracking_enter()
> __context_tracking_enter()
> vtime_user_enter()
>
> expects preemption to be disabled. It effectively is, because local
> interrupts are disabled by context_tracking_enter().
>
> However, the requirement for preemption to be disabled is not
> documented... so shrug. Maybe someone can say what the real requirements
> are here.
>From dealing with this recently on arm64, theis is a bit messy. To
handle this robustly we need to do a few things in sequence, including
using the *_irqoff() variants of the context_tracking_user_*()
functions.
I wrote down the constraints in commit:
23529049c6842382 ("arm64: entry: fix non-NMI user<->kernel transitions")
For user->kernel transitions, the arch code needs the following sequence
before invoking arbitrary kernel C code:
lockdep_hardirqs_off(CALLER_ADDR0);
user_exit_irqoff();
trace_hardirqs_off_finish();
For kernel->user transitions, the arch code needs the following sequence
once it will no longer invoke arbitrary kernel C code, just before
returning to userspace:
trace_hardirqs_on_prepare();
lockdep_hardirqs_on_prepare(CALLER_ADDR0);
user_enter_irqoff();
lockdep_hardirqs_on(CALLER_ADDR0);
Thanks,
Mark.
Re: [syzbot] upstream boot error: WARNING in __context_tracking_enter
On Fri, Mar 19, 2021 at 10:54:48AM +0100, Dmitry Vyukov wrote: > .On Fri, Mar 19, 2021 at 10:44 AM syzbot > wrote: > > syzbot found the following issue on: > > > > HEAD commit:8b12a62a Merge tag 'drm-fixes-2021-03-19' of git://anongit.. > > git tree: upstream > > console output: https://syzkaller.appspot.com/x/log.txt?x=17e815aed0 > > kernel config: https://syzkaller.appspot.com/x/.config?x=cfeed364fc353c32 > > dashboard link: https://syzkaller.appspot.com/bug?extid=f09a12b2c77bfbbf51bd > > userspace arch: arm > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+f09a12b2c77bfbbf5...@syzkaller.appspotmail.com > > > +Mark, arm > It did not get far with CONFIG_CONTEXT_TRACKING_FORCE (kernel doesn't boot). It seems that the path: context_tracking_user_enter() user_enter() context_tracking_enter() __context_tracking_enter() vtime_user_enter() expects preemption to be disabled. It effectively is, because local interrupts are disabled by context_tracking_enter(). However, the requirement for preemption to be disabled is not documented... so shrug. Maybe someone can say what the real requirements are here. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
Re: [syzbot] upstream boot error: WARNING in __context_tracking_enter
.On Fri, Mar 19, 2021 at 10:44 AM syzbot wrote: > > Hello, > > syzbot found the following issue on: > > HEAD commit:8b12a62a Merge tag 'drm-fixes-2021-03-19' of git://anongit.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=17e815aed0 > kernel config: https://syzkaller.appspot.com/x/.config?x=cfeed364fc353c32 > dashboard link: https://syzkaller.appspot.com/bug?extid=f09a12b2c77bfbbf51bd > userspace arch: arm > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+f09a12b2c77bfbbf5...@syzkaller.appspotmail.com +Mark, arm It did not get far with CONFIG_CONTEXT_TRACKING_FORCE (kernel doesn't boot). > Run /sbin/init as init process > [ cut here ] > WARNING: CPU: 0 PID: 1 at include/linux/seqlock.h:271 __seqprop_assert > include/linux/seqlock.h:271 [inline] > WARNING: CPU: 0 PID: 1 at include/linux/seqlock.h:271 > __seqprop_assert.constprop.0+0xf0/0x11c include/linux/seqlock.h:269 > Modules linked in: > Kernel panic - not syncing: panic_on_warn set ... > CPU: 0 PID: 1 Comm: init Not tainted 5.12.0-rc3-syzkaller #0 > Hardware name: ARM-Versatile Express > Backtrace: > [<81804310>] (dump_backtrace) from [<81804584>] (show_stack+0x18/0x1c > arch/arm/kernel/traps.c:252) > r7:0080 r6:6193 r5: r4:82b58444 > [<8180456c>] (show_stack) from [<8180bc58>] (__dump_stack lib/dump_stack.c:79 > [inline]) > [<8180456c>] (show_stack) from [<8180bc58>] (dump_stack+0xb8/0xe8 > lib/dump_stack.c:120) > [<8180bba0>] (dump_stack) from [<81805118>] (panic+0x130/0x378 > kernel/panic.c:231) > r7:81f487d4 r6:82a390e4 r5: r4:82c6b0d8 > [<81804fe8>] (panic) from [<802447b4>] (__warn+0xb0/0x164 kernel/panic.c:605) > r3:82a2248c r2: r1:5b71e000 r0:81f487d4 > r7:010f > [<80244704>] (__warn) from [<818053c8>] (warn_slowpath_fmt+0x68/0xd4 > kernel/panic.c:628) > r7:8028c4b4 r6:010f r5:81f40c30 r4: > [<81805364>] (warn_slowpath_fmt) from [<8028c4b4>] (__seqprop_assert > include/linux/seqlock.h:271 [inline]) > [<81805364>] (warn_slowpath_fmt) from [<8028c4b4>] > (__seqprop_assert.constprop.0+0xf0/0x11c include/linux/seqlock.h:269) > r8: r7:82a22498 r6:828ac940 r5:8181fbb0 r4:0001 > [<8028c3c4>] (__seqprop_assert.constprop.0) from [<8028ea54>] > (vtime_user_enter+0x1c/0x90 kernel/sched/cputime.c:709) > r5:8181fbb0 r4:834f > [<8028ea38>] (vtime_user_enter) from [<8181fbb0>] > (__context_tracking_enter+0x148/0x334 kernel/context_tracking.c:82) > r7:82a22498 r6:828ac940 r5:e000 r4:0001 > [<8181fa68>] (__context_tracking_enter) from [<80417170>] > (context_tracking_enter kernel/context_tracking.c:122 [inline]) > [<8181fa68>] (__context_tracking_enter) from [<80417170>] > (context_tracking_enter+0x54/0x84 kernel/context_tracking.c:106) > r7: r6: r5:6193 r4:0001 > [<8041711c>] (context_tracking_enter) from [<804171bc>] (user_enter > include/linux/context_tracking.h:28 [inline]) > [<8041711c>] (context_tracking_enter) from [<804171bc>] > (context_tracking_user_enter+0x1c/0x20 kernel/context_tracking.c:130) > r5:81820218 r4: > [<804171a0>] (context_tracking_user_enter) from [<802000d4>] > (no_work_pending+0x8/0x38) > Exception stack(0x834dffb0 to 0x834dfff8) > ffa0: > ffc0: > ffe0: 7ec68ef0 76ee5a00 0010 > Rebooting in 86400 seconds.. > > > --- > This report 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 syzkal...@googlegroups.com. > > syzbot will keep track of this issue. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > -- > You received this message because you are subscribed to the Google Groups > "syzkaller-bugs" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to syzkaller-bugs+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/syzkaller-bugs/4f14c105bde08f75%40google.com.
[syzbot] upstream boot error: WARNING in __context_tracking_enter
Hello, syzbot found the following issue on: HEAD commit:8b12a62a Merge tag 'drm-fixes-2021-03-19' of git://anongit.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17e815aed0 kernel config: https://syzkaller.appspot.com/x/.config?x=cfeed364fc353c32 dashboard link: https://syzkaller.appspot.com/bug?extid=f09a12b2c77bfbbf51bd userspace arch: arm IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+f09a12b2c77bfbbf5...@syzkaller.appspotmail.com l2tp_core: L2TP core driver, V2.0 l2tp_ip: L2TP IP encapsulation support (L2TPv3) l2tp_netlink: L2TP netlink interface l2tp_eth: L2TP ethernet pseudowire support (L2TPv3) l2tp_ip6: L2TP IP encapsulation support for IPv6 (L2TPv3) 8021q: 802.1Q VLAN Support v1.8 sctp: Hash tables configured (bind 64/102) NET: Registered protocol family 21 Registered RDS/infiniband transport Registered RDS/tcp transport NET: Registered protocol family 43 9pnet: Installing 9P2000 support Key type dns_resolver registered Key type ceph registered libceph: loaded (mon/osd proto 15/24) NET: Registered protocol family 40 Registering SWP/SWPB emulation handler registered taskstats version 1 Loading compiled-in X.509 certificates Loaded X.509 cert 'Build time autogenerated kernel key: f850c787ad998c396ae089c083b940ff0a9abb77' zswap: loaded using pool lzo/zbud Key type ._fscrypt registered Key type .fscrypt registered Key type fscrypt-provisioning registered Key type big_key registered Key type encrypted registered ima: No TPM chip found, activating TPM-bypass! ima: Allocated hash algorithm: sha256 ima: No architecture policies found evm: Initialising EVM extended attributes: evm: security.selinux evm: security.ima evm: security.capability evm: HMAC attrs: 0x1 printk: console [netcon0] enabled netconsole: network logging started gtp: GTP module loaded (pdp ctx size 64 bytes) ALSA device list: #0: Dummy 1 #1: Loopback 1 #2: Virtual MIDI Card 1 #3: ARM AC'97 Interface PL041 rev0 at 0x1c04, irq 36 uart-pl011 1c09.serial: no DMA platform data md: Skipping autodetection of RAID arrays. (raid=autodetect will force) EXT4-fs (vda): mounted filesystem without journal. Opts: (null). Quota mode: none. VFS: Mounted root (ext4 filesystem) readonly on device 253:0. devtmpfs: mounted Freeing unused kernel memory: 2048K Run /sbin/init as init process [ cut here ] WARNING: CPU: 0 PID: 1 at include/linux/seqlock.h:271 __seqprop_assert include/linux/seqlock.h:271 [inline] WARNING: CPU: 0 PID: 1 at include/linux/seqlock.h:271 __seqprop_assert.constprop.0+0xf0/0x11c include/linux/seqlock.h:269 Modules linked in: Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 1 Comm: init Not tainted 5.12.0-rc3-syzkaller #0 Hardware name: ARM-Versatile Express Backtrace: [<81804310>] (dump_backtrace) from [<81804584>] (show_stack+0x18/0x1c arch/arm/kernel/traps.c:252) r7:0080 r6:6193 r5: r4:82b58444 [<8180456c>] (show_stack) from [<8180bc58>] (__dump_stack lib/dump_stack.c:79 [inline]) [<8180456c>] (show_stack) from [<8180bc58>] (dump_stack+0xb8/0xe8 lib/dump_stack.c:120) [<8180bba0>] (dump_stack) from [<81805118>] (panic+0x130/0x378 kernel/panic.c:231) r7:81f487d4 r6:82a390e4 r5: r4:82c6b0d8 [<81804fe8>] (panic) from [<802447b4>] (__warn+0xb0/0x164 kernel/panic.c:605) r3:82a2248c r2: r1:5b71e000 r0:81f487d4 r7:010f [<80244704>] (__warn) from [<818053c8>] (warn_slowpath_fmt+0x68/0xd4 kernel/panic.c:628) r7:8028c4b4 r6:010f r5:81f40c30 r4: [<81805364>] (warn_slowpath_fmt) from [<8028c4b4>] (__seqprop_assert include/linux/seqlock.h:271 [inline]) [<81805364>] (warn_slowpath_fmt) from [<8028c4b4>] (__seqprop_assert.constprop.0+0xf0/0x11c include/linux/seqlock.h:269) r8: r7:82a22498 r6:828ac940 r5:8181fbb0 r4:0001 [<8028c3c4>] (__seqprop_assert.constprop.0) from [<8028ea54>] (vtime_user_enter+0x1c/0x90 kernel/sched/cputime.c:709) r5:8181fbb0 r4:834f [<8028ea38>] (vtime_user_enter) from [<8181fbb0>] (__context_tracking_enter+0x148/0x334 kernel/context_tracking.c:82) r7:82a22498 r6:828ac940 r5:e000 r4:0001 [<8181fa68>] (__context_tracking_enter) from [<80417170>] (context_tracking_enter kernel/context_tracking.c:122 [inline]) [<8181fa68>] (__context_tracking_enter) from [<80417170>] (context_tracking_enter+0x54/0x84 kernel/context_tracking.c:106) r7: r6: r5:6193 r4:0001 [<8041711c>] (context_tracking_enter) from [<804171bc>] (user_enter include/linux/context_tracking.h:28 [inline]) [<8041711c>] (context_tracking_enter) from [<804171bc>] (context_tracking_user_enter+0x1c/0x20 kernel/context_tracking.c:130) r5:81820218 r4: [<804171a0>] (context_tracking_user_enter) from [<802000d4>] (no_work_pending+0x8/0x38) Exception stack(0x834dffb0 to 0x834dfff8) ffa0: ffc0:
