lkml.org 
[lkml]   [2013]   [Nov]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: /proc/vmcore mmap() failure issue
    On Wed, Nov 20, 2013 at 05:29:16AM +0000, Atsushi Kumagai wrote:
    > On 2013/11/18 22:56:10, kexec <kexec-bounces@lists.infradead.org> wrote:
    > > On Mon, Nov 18, 2013 at 12:51:39AM +0000, Atsushi Kumagai wrote:
    > >
    > > [..]
    > > > > Is there any chance that you could look into fixing this. I have no
    > > > > experience writing code for makedumpfile.
    > > >
    > > > I'll send a patch to fix this soon.
    > >
    > > Thanks Atsushi.
    > >
    > > Vivek
    >
    > Vivek, could you test this patch ?
    >
    > Thanks
    > Atsushi Kumagai
    >
    >
    > From: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>
    > Date: Wed, 20 Nov 2013 10:05:03 +0900
    > Subject: [PATCH] Disable mmap() for reading fractional pages.
    >
    > Since mmap() was introduced on /proc/vmcore, it fails
    > for fractional pages which don't start or end at page boundary
    > due to kernel issue.
    > This patch disables mmap() temporarily for fractional pages
    > to avoid this issue, so mmap() will be used only for aligned pages.
    >
    > Signed-off-by: Atsushi Kumagai <kumagai-atsushi@mxc.nes.nec.co.jp>

    Hi Atsushi,

    Even with this patch applied I see mmap() failure.

    mem_map (39)
    mem_map : ffffea0004e00000
    pfn_start : 138000
    pfn_end : 140000
    read /proc/vmcore with mmap()
    Excluding unnecessary pages : [100.0 %] |STEP [Excluding
    unnecessary pages] : 0.035925 seconds
    Excluding unnecessary pages : [100.0 %] \STEP [Excluding
    unnecessary pages] : 0.035774 seconds
    Excluding unnecessary pages : [100.0 %] -STEP [Excluding
    unnecessary pages] : 0.035229 seconds
    Copying data : [ 40.9 %] -Can't map
    [b98fd000-b9cfd000] with mmap()
    read_from_vmcore: Can't read the dump memory(/proc/vmcore) with mmap().
    readpage_elf: Can't read the dump memory(/proc/vmcore).
    readmem: type_addr: 1, addr:bffba000, size:4096
    read_pfn: Can't get the page data.
    Resource temporarily unavailable
    makedumpfile Failed.
    kdump: saving vmcore failed

    Following is part of /proc/iomem on my system.

    00100000-bffc283f : System RAM
    01000000-018c551d : Kernel code
    018c551e-01ef3f3f : Kernel data
    0204a000-02984fff : Kernel bss
    2e000000-35ffffff : Crash kernel
    bffc2840-bfffffff : reserved

    This is a different system than what I used last time. So I am not sure
    if this is same error or something else. But one thing is clear that
    System RAM last page is partial and we should face mmap() failure.

    Thanks
    Vivek


    \
     
     \ /
      Last update: 2013-11-20 16:21    [W:4.711 / U:0.000 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site