lkml.org 
[lkml]   [2017]   [Jan]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH 2/2] base/memory, hotplug: fix a kernel oops in show_valid_zones()
    On Thu, Jan 26, 2017 at 10:26:23PM +0000, Kani, Toshimitsu wrote:
    > On Thu, 2017-01-26 at 13:52 -0800, Andrew Morton wrote:
    > > On Thu, 26 Jan 2017 14:44:15 -0700 Toshi Kani <toshi.kani@hpe.com>
    > > wrote:
    > >
    > > > Reading a sysfs memoryN/valid_zones file leads to the following
    > > > oops when the first page of a range is not backed by struct page.
    > > > show_valid_zones() assumes that 'start_pfn' is always valid for
    > > > page_zone().
    > > >
    > > >  BUG: unable to handle kernel paging request at ffffea017a000000
    > > >  IP: show_valid_zones+0x6f/0x160
    > > >
    > > > Since test_pages_in_a_zone() already checks holes, extend this
    > > > function to return 'valid_start' and 'valid_end' for a given range.
    > > > show_valid_zones() then proceeds with the valid range.
    > >
    > > This doesn't apply to current mainline due to changes in
    > > zone_can_shift().  Please redo and resend.
    >
    > Sorry, I will rebase to the -mm tree and resend the patches.
    >
    > > Please also update the changelog to provide sufficient information
    > > for others to decide which kernel(s) need the fix.  In particular:
    > > under what circumstances will it occur?  On real machines which real
    > > people own?
    >
    > Yes, this issue happens on real x86 machines with 64GiB or more memory.
    > On such systems, the memory block size is bumped up to 2GiB. [1]
    >
    > Here is an example system. 0x3240000000 is only aligned by 1GiB and
    > its memory block starts from 0x3200000000, which is not backed by
    > struct page.
    >
    >  BIOS-e820: [mem 0x0000003240000000-0x000000603fffffff] usable
    >
    > I will add the descriptions to the patch.

    Should it also be backported to the stable kernels to resolve the issue
    there?

    thanks,

    greg k-h

    \
     
     \ /
      Last update: 2017-01-27 08:49    [W:5.351 / U:0.008 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site