linux-kernel - Re: [GIT PULL] x86/topology changes for v5.3

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Message-ID: <20190710132144.GM3402@hirez.programming.kicks-ass.net>
Date:   Wed, 10 Jul 2019 15:21:44 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Jiri Kosina <jikos@...nel.org>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Xi Ruoyao <xry111@...gyan1223.wang>,
        Kees Cook <keescook@...omium.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Ingo Molnar <mingo@...nel.org>,
        Linux List Kernel Mailing <linux-kernel@...r.kernel.org>,
        Borislav Petkov <bp@...en8.de>, Len Brown <lenb@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        Tony Luck <tony.luck@...el.com>,
        Bob Moore <robert.moore@...el.com>,
        Erik Schmauss <erik.schmauss@...el.com>,
        Josh Poimboeuf <jpoimboe@...hat.com>,
        Daniel Bristot de Oliveira <bristot@...hat.com>,
        Nadav Amit <namit@...are.com>
Subject: Re: [GIT PULL] x86/topology changes for v5.3

On Wed, Jul 10, 2019 at 02:31:29PM +0200, Jiri Kosina wrote:
> On Wed, 10 Jul 2019, Thomas Gleixner wrote:
> 
> > From the log:
> > 
> > BUG: unable to handle page fault for address: ffffffff9edc1598
> > #PF: supervisor write access in kernel mode
> > #PF: error_code(0x0003) - permissions violation
> > PGD 1a20c067 P4D 1a20c067 PUD 1a20d063 PMD 8000000019e000e1 
> > Oops: 0003 [#1] SMP PTI
> > 2 PID: 151 Comm: systemd-udevd Not tainted 5.2.0+ #54
> > Hardware name: LENOVO 20175/INVALID, BIOS 66CN54WW 01/21/2013
> > RIP: 0010:static_key_set_mod.isra.0+0x10/0x30
> > Code: 48 8b 37 83 e6 03 48 09 c6 48 89 37 c3 66 66 2e 0f 1f 84 00 00 00 00 00 66 90 48 89 f0 a8 03 75 0d 48 8b 37 83 e6 03 48 09 c6 <48> 89 37 c3 0f 0b 48 8b 37 83 e6 03 48 09 c6 48 89 37 c3 66 66 2e
> > RSP: 0000:ffffa606c032bc98 EFLAGS: 00010286
> > RAX: ffff9981ddce30a0 RBX: ffffffff9edc1590 RCX: 0000000000000000
> > RDX: 0000000000000020 RSI: ffff9981ddce30a0 RDI: ffffffff9edc1598
> > RBP: ffffffffc06f4000 R08: ffff9981e6003980 R09: ffff9981ddce30a0
> > R10: 0000000000000000 R11: 0000000000028b56 R12: ffffffffc06f8880
> > R13: ffff9981ddce3080 R14: ffffffffc06f4008 R15: ffffffffc06f6dc0
> > FS:  00007f992dd9a680(0000) GS:ffff9981e7080000(0000) knlGS:0000000000000000
> > CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: ffffffff9edc1598 CR3: 00000002233aa001 CR4: 00000000001606e0
> > Call Trace:
> >   jump_label_module_notify+0x1e7/0x2b0
> >   notifier_call_chain+0x44/0x70
> >   blocking_notifier_call_chain+0x43/0x60
> >   load_module+0x1bcb/0x2490
> >   ? vfs_read+0x11f/0x150
> >   ? __do_sys_finit_module+0xbf/0xe0
> >   __do_sys_finit_module+0xbf/0xe0
> >   do_syscall_64+0x43/0x110
> >   entry_SYSCALL_64_after_hwframe+0x44/0xa9
> > 
> > Josh, didn't you mention that yesterday or so?
> 
> That's what Tony yesterday indicated on IRC that his system is suffering 
> from as well.
> 
> Adding Daniel to check whether this couldn't be some fallout of jumplabel 
> batching.

AFAICT this is _before_ we get to patching. The function that explodes
is static_key_set_mod(), as called from jump_label_add_module().

What that function does is for all patch sites in the module, find the
corresponding key; if that key is not also in that module, allocate a
static_key_mod structure and link the module entries to the key. Such
that we can find all instances from a given key.

I don't think anything here has changed in a while.