linux-kernel - Re: kmemleak panic

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Date:   Tue, 22 Jan 2019 13:50:19 +0530
From:   Prateek Patel <prpatel@...dia.com>
To:     Marc Gonzalez <marc.w.gonzalez@...e.fr>,
        Rob Herring <robh+dt@...nel.org>,
        Robin Murphy <robin.murphy@....com>,
        Sachin Nikam <snikam@...dia.com>,
        John Hubbard <jhubbard@...dia.com>,
        Ralph Campbell <rcampbell@...dia.com>
CC:     Catalin Marinas <catalin.marinas@....com>,
        Frank Rowand <frowand.list@...il.com>,
        Marek Szyprowski <m.szyprowski@...sung.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Mark Rutland <mark.rutland@....com>,
        Arnd Bergmann <arnd@...db.de>,
        Ard Biesheuvel <ard.biesheuvel@...aro.org>,
        Oscar Salvador <osalvador@...e.de>,
        Wei Yang <richard.weiyang@...il.com>,
        Michal Hocko <mhocko@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Qian Cai <cai@....pw>, LKML <linux-kernel@...r.kernel.org>,
        Vinayak Menon <vinmenon@...eaurora.org>
Subject: Re: kmemleak panic


On 1/21/2019 7:24 PM, Marc Gonzalez wrote:
> On 21/01/2019 14:35, Rob Herring wrote:
>
>> On Mon, Jan 21, 2019 at 6:19 AM Robin Murphy wrote:
>>> On 21/01/2019 11:57, Marc Gonzalez wrote:
>>> [...]
>>>> # echo dump=0xffffffc021e00000 > /sys/kernel/debug/kmemleak
>>>> kmemleak: Object 0xffffffc021e00000 (size 2097152):
>>>> kmemleak:   comm "swapper/0", pid 0, jiffies 4294892296
>>>> kmemleak:   min_count = 0
>>>> kmemleak:   count = 0
>>>> kmemleak:   flags = 0x1
>>>> kmemleak:   checksum = 0
>>>> kmemleak:   backtrace:
>>>>        kmemleak_alloc_phys+0x48/0x60
>>>>        memblock_alloc_range_nid+0x8c/0xa4
>>>>        memblock_alloc_base_nid+0x4c/0x60
>>>>        __memblock_alloc_base+0x3c/0x4c
>>>>        early_init_dt_alloc_reserved_memory_arch+0x54/0xa4
>>>>        fdt_init_reserved_mem+0x308/0x3ec
>>>>        early_init_fdt_scan_reserved_mem+0x88/0xb0
>>>>        arm64_memblock_init+0x1dc/0x254
>>>>        setup_arch+0x1c8/0x4ec
>>>>        start_kernel+0x84/0x44c
>>>>        0xffffffffffffffff
>>> OK, so via the __va(phys) call in kmemleak_alloc_phys(), you end up with
>>> the linear map address of a no-map reservation, which unsurprisingly
>>> turns out not to be mapped. Is there a way to tell kmemleak that it
>>> can't scan within a particular object?

Yes,  kmemleak_no_scan() do this which is done in patch 
https://patchwork.ozlabs.org/patch/995367/

This was done to avoid kmemleak scanning on the blocks which are nomaped 
and should not have linear mapping created in kernel page table.

>> There was this patch posted[1]. I never got a reply, so it hasn't been applied.
>>
>> Rob
>>
>> https://patchwork.ozlabs.org/patch/995367/
> It is worth noting that the author's email address appears to be dead.
> <schowdary@...dia.com>: host hqemgate08.nvidia.com[216.228.121.117] said:
> 550 #5.1.0 Address rejected. (in reply to RCPT TO command)
>
> Adding a few nvidia devs for comment.