| lists.openwall.net | lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC | |
|
Open Source and information security mailing list archives
| ||
|
Message-ID: <20201113171648.GI3249@paulmck-ThinkPad-P72>
Date: Fri, 13 Nov 2020 09:16:48 -0800
From: "Paul E. McKenney" <paulmck@...nel.org>
To: Peter Zijlstra <peterz@...radead.org>
Cc: eupm90@...il.com, Thomas Gleixner <tglx@...utronix.de>,
linux-kernel@...r.kernel.org, x86@...nel.org
Subject: Re: #PF from NMI
On Fri, Nov 13, 2020 at 01:53:32PM +0100, Peter Zijlstra wrote:
> Hi
>
> Eugenio reported
> (https://bugzilla.kernel.org/attachment.cgi?id=293659&action=edit):
>
> [ 139.226723] ------------[ cut here ]------------
> [ 139.226724] WARNING: CPU: 9 PID: 2290 at kernel/rcu/tree.c:932 __rcu_irq_enter_check_tick+0x84/0xd0
> [ 139.226725] Modules linked in: xt_CHECKSUM xt_MASQUERADE xt_conntrack ipt_REJECT nf_reject_ipv4 nft_compat nft_counter nft_chain_nat nf_e
> [ 139.226746] CPU: 9 PID: 2290 Comm: perf Tainted: G S 5.10.0-rc2+ #1
> [ 139.226746] Hardware name: Dell Inc. PowerEdge R430/0CN7X8, BIOS 2.6.0 10/31/2017
> [ 139.226747] RIP: 0010:__rcu_irq_enter_check_tick+0x84/0xd0
> [ 139.226747] Code: 75 cc 48 8b 7b 18 e8 4b c9 84 00 80 bb 05 01 00 00 00 74 09 80 bb 06 01 00 00 00 74 11 48 8b 7b 18 c6 07 00 0f 1f 40 00
> [ 139.226748] RSP: 0000:ffffbdb38586b8c8 EFLAGS: 00010006
> [ 139.226749] RAX: 0000000080110000 RBX: ffff9cdc2f92b9c0 RCX: ffffffff9f600fb7
> [ 139.226749] RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffffbdb38586b938
> [ 139.226749] RBP: 000000000000000e R08: 0000000000000000 R09: 0000000000000000
> [ 139.226750] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
> [ 139.226750] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> [ 139.226750] FS: 00007fb0c5a628c0(0000) GS:ffff9cdc2f900000(0000) knlGS:0000000000000000
> [ 139.226751] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [ 139.226751] CR2: 000000000000000e CR3: 000000010e0ea001 CR4: 00000000003706a0
> [ 139.226752] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> [ 139.226752] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> [ 139.226752] Call Trace:
> [ 139.226753] irqentry_enter+0x25/0x40
> [ 139.226753] exc_page_fault+0x38/0x4c0
> [ 139.226753] asm_exc_page_fault+0x1e/0x30
> [ 139.226753] RIP: 0010:__get_user_nocheck_8+0x6/0x13
> [ 139.226754] Code: 01 ca c3 90 0f 01 cb 0f ae e8 0f b7 10 31 c0 0f 01 ca c3 90 0f 01 cb 0f ae e8 8b 10 31 c0 0f 01 ca c3 66 90 0f 01 cb 0f
> [ 139.226754] RSP: 0000:ffffbdb38586b9e8 EFLAGS: 00050087
> [ 139.226755] RAX: 000000000000000e RBX: ffffbdb38586ba30 RCX: 00007fb0c586f0d2
> [ 139.226756] RDX: 0000000000000080 RSI: 000000000000007f RDI: 00000000ffffdff0
> [ 139.226756] RBP: ffffbdb38586bf58 R08: 00000000bffffff0 R09: ffffffffa05a0460
> [ 139.226756] R10: 00ffffffffffeff0 R11: 00007fffffffeff0 R12: 000000000000000e
> [ 139.226757] R13: ffff9cd4daa017c0 R14: 0000000000000000 R15: 000000000000007f
> [ 139.226757] ? kvmclock_cpu_down_prep+0x20/0x20 [kvm]
> [ 139.226757] perf_callchain_user+0xf4/0x280
> [ 139.226758] get_perf_callchain+0x17b/0x1b0
> [ 139.226758] perf_callchain+0x71/0x80
> [ 139.226758] setup_pebs_fixed_sample_data+0x2a8/0x360
> [ 139.226759] intel_pmu_drain_pebs_nhm+0x477/0x5d0
> [ 139.226759] ? get_page_from_freelist+0x117d/0x1390
> [ 139.226759] ? page_counter_cancel+0x1f/0x30
> [ 139.226760] ? page_counter_uncharge+0x1d/0x30
> [ 139.226760] ? drain_stock.isra.54+0x64/0xb0
> [ 139.226760] ? get_page_from_freelist+0x117d/0x1390
> [ 139.226761] handle_pmi_common+0xc3/0x2d0
> [ 139.226761] ? alloc_set_pte+0xd3/0x5e0
> [ 139.226761] ? filemap_map_pages+0x2d2/0x430
> [ 139.226762] ? xfs_filemap_map_pages+0x44/0x60 [xfs]
> [ 139.226762] ? xfs_iunlock+0x86/0xd0 [xfs]
> [ 139.226762] ? handle_mm_fault+0x145b/0x1650
> [ 139.226762] intel_pmu_handle_irq+0xc9/0x1c0
> [ 139.226763] perf_event_nmi_handler+0x24/0x40
> [ 139.226763] nmi_handle+0x55/0x130
> [ 139.226763] default_do_nmi+0x49/0x100
> [ 139.226764] exc_nmi+0x121/0x150
> [ 139.226764] asm_exc_nmi+0x8e/0xd7
> [ 139.226764] RIP: 0033:0x7fb0c586f0d2
> [ 139.226765] Code: 48 89 44 24 30 48 8b 83 00 03 00 00 48 85 c0 0f 84 d3 00 00 00 48 8b 7c 24 20 8b 8b fc 02 00 00 8b 54 24 38 23 93 f8 08
> [ 139.226766] RSP: 002b:00007ffcf13cde60 EFLAGS: 00010246
> [ 139.226766] RAX: 00007fb0c309c2b0 RBX: 00007fb0c5a73500 RCX: 0000000000000006
> [ 139.226766] RDX: 0000000000000000 RSI: 000000000000000a RDI: 00000000fc2c9fd0
> [ 139.226767] RBP: 000000000000000e R08: 00007ffcf13cdf90 R09: 00007fb0c5a8f410
> [ 139.226767] R10: 000000000000002b R11: 0000000000000246 R12: 0000000000000000
> [ 139.226768] R13: 0000000000000001 R14: 00007fb0c32a1fbc R15: 00007fb0c5a69cd0
>
> Which is a #PF from NMI context, which is perfectly fine. However
> __rcu_irq_enter_check_tick() is triggering WARN.
>
> AFAICT the right thing is to simply remove the warn like so.
I have to defer to you guys on this one.
But is a corresponding change required on return-from-NMI side?
Looks OK to me at first glance, but I could be missing something.
Plus I am most likely looking at the wrong version of the x86
entry/exit code. :-/
Thanx, Paul
> ---
> diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
> index 430ba58d8bfe..9bda92d8b914 100644
> --- a/kernel/rcu/tree.c
> +++ b/kernel/rcu/tree.c
> @@ -928,8 +928,8 @@ void __rcu_irq_enter_check_tick(void)
> {
> struct rcu_data *rdp = this_cpu_ptr(&rcu_data);
>
> - // Enabling the tick is unsafe in NMI handlers.
> - if (WARN_ON_ONCE(in_nmi()))
> + // if we're here from NMI, there's nothing to do.
> + if (in_nmi())
> return;
>
> RCU_LOCKDEP_WARN(rcu_dynticks_curr_cpu_in_eqs(),
Powered by blists - more mailing lists