linux-kernel - Re: [BUG -tip] kmemleak and stacktrace cause page faul

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Message-ID: <20191022145619.GE12121@uranus.lan>
Date:   Tue, 22 Oct 2019 17:56:19 +0300
From:   Cyrill Gorcunov <gorcunov@...il.com>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>, linux-mm@...ck.org,
        Catalin Marinas <catalin.marinas@....com>
Subject: Re: [BUG -tip] kmemleak and stacktrace cause page faul

On Tue, Oct 22, 2019 at 05:23:25PM +0300, Cyrill Gorcunov wrote:
> 
> I presume the kmemleak tries to save stack trace too early when estack_pages are not
> yet filled.

Indeed, at this stage of boot the percpu_setup_exception_stacks has not been called
yet and estack_pages full of crap

[    0.157502] stk 0x1008 k 1 begin 0x0 end 0xd000 estack_pages 0xffffffff82014880 ep 0xffffffff82014888
[    0.159395] estack_pages[0] = 0x0
[    0.160046] estack_pages[1] = 0x5100000001000
[    0.160881] estack_pages[2] = 0x0
[    0.161530] estack_pages[3] = 0x6100000003000
[    0.162343] estack_pages[4] = 0x0
[    0.162962] estack_pages[5] = 0x0
[    0.163523] estack_pages[6] = 0x0
[    0.164065] estack_pages[7] = 0x8100000007000
[    0.164978] estack_pages[8] = 0x0
[    0.165624] estack_pages[9] = 0x9100000009000
[    0.166448] estack_pages[10] = 0x0
[    0.167064] estack_pages[11] = 0xa10000000b000
[    0.168055] estack_pages[12] = 0x0
[    0.168891] BUG: unable to handle page fault for address: 0000000000001ff0