lkml.org 
[lkml]   [2023]   [Feb]   [27]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    SubjectRe: [PATCH RFC] arm64/vmalloc: use module region only for module_alloc() if CONFIG_RANDOMIZE_BASE is set
    From


    On 27.02.23 17:14, Ard Biesheuvel wrote:
    > On Mon, 27 Feb 2023 at 16:08, Linux regression tracking (Thorsten
    > Leemhuis) <regressions@leemhuis.info> wrote:
    >>
    >> [CCing the regression list, as it should be in the loop for regressions:
    >> https://docs.kernel.org/admin-guide/reporting-regressions.html]
    >>
    >> On 07.02.23 12:29, Will Deacon wrote:
    >>> On Tue, Jan 31, 2023 at 05:03:32PM +0100, Ard Biesheuvel wrote:
    >>>> On Tue, 31 Jan 2023 at 16:07, Will Deacon <will@kernel.org> wrote:
    >>>>> On Tue, Jan 31, 2023 at 03:06:44PM +0000, Will Deacon wrote:
    >>>>>> On Sun, Jan 29, 2023 at 01:41:47PM -0800, Andrew Morton wrote:
    >>>>>>> On Sun, 29 Jan 2023 10:44:31 +0800 Liu Shixin <liushixin2@huawei.com> wrote:
    >>>>>>>> On 2022/12/27 17:26, Liu Shixin wrote:
    >>>>>>>>> After I add a 10GB pmem device, I got the following error message when
    >>>>>>>>> insert module:
    >>>>>>>>>
    >>>>>>>>> insmod: vmalloc error: size 16384, vm_struct allocation failed,
    >>>>>>>>> mode:0xcc0(GFP_KERNEL), nodemask=(null),cpuset=/,mems_allowed=0
    >>>>>>>>>
    >>>>>>>>> If CONFIG_RANDOMIZE_BASE is set, the module region can be located in the
    >>>>>>>>> vmalloc region entirely. Although module_alloc() can fall back to a 2GB
    >>>>>>>>> window if ARM64_MODULE_PLTS is set, the module region is still easily
    >>>>>>>>> exhausted because the module region is located at bottom of vmalloc region
    >>>>>>>>> and the vmalloc region is allocated from bottom to top.
    >>>>>>>>>
    >>>>>>>>> Skip module region if not calling from module_alloc().
    >>>>>>>
    >>>>>>> I'll assume this is for the arm tree.
    >>>>>>>
    >>>>>>> Acked-by: Andrew Morton <akpm@linux-foundation.org>
    >>>>>>
    >>>>>> This looks like the same issue previously reported at:
    >>>>>>
    >>>>>> https://lore.kernel.org/all/e6a804de-a5f7-c551-ffba-e09d04e438fc@hisilicon.com/
    >>>>>>
    >>>>>> where Ard had a few suggestions but, afaict, they didn't help.
    >>>>>>
    >>>>
    >>>> Thanks for the cc.
    >>>>
    >>>> So this is a bit clunky, and I wonder whether we wouldn't be better
    >>>> off just splitting the vmalloc region into two separate regions: one
    >>>> for the kernel and modules, and one for everything else. That way, we
    >>>> lose one bit of entropy in the randomized placement, but the default
    >>>> 48-bit VA space is vast anway, and even on 39-bit VA configs (such as
    >>>> Android), I seriously doubt that we come anywhere close to exhausting
    >>>> the vmalloc space today.
    >>>
    >>> That sounds like a good idea to me.
    >>>
    >>> Liu Shixin -- do you think you could have a go at implementing Ard's
    >>> suggestion instead?
    >>
    >> Liu Shixin, did you ever look into realizing this idea?
    >>
    >> Or was some progress already made and I just missed it?
    >
    > This patch
    >
    > https://lore.kernel.org/all/20230223204101.1500373-1-ardb@kernel.org/
    >
    > should fix the issue.

    Great, many thx.

    >> I'm asking, as the idea discussed afaics is not only supposed to fix the
    >> regression you tried to address, but also one that is now three months
    >> old and stalled since Mid-December -- which is really unfortunate, as
    >> that's not how regressions should be handled. :-/
    >
    > Is it documented anywhere how regressions should be handled?

    https://docs.kernel.org/process/handling-regressions.html

    Side note: that also mentions use of the "Link" tag. If the patch had
    one, I'd noticed it and wouldn't bothered anyone here.

    > The
    > mailing list is flooded with hard to reproduce reports from users as
    > well as automatic fuzzers and build bots, so I don't think it is
    > entirely unreasonable to move unresponsive reporters to the back of
    > the queue.

    I do that sometimes, but fwiw, from what I can see it wasn't a reporter
    that was unresponsive:

    https://lore.kernel.org/linux-arm-kernel/c1ff5cae-7f56-7fdb-c832-ffbcc177535b@leemhuis.info/

    But I might be missing something, sorry if I do. And there was the
    festive season what complicated everything. Whatever, as long as this
    this is fixed.

    /me wonders if we should ask "chenxiang (M)" to test that patch, too;
    but /me is not even totally sure it's the same problem

    >> But well, it afaik was
    >> caused by a patch from Ard, so it's obviously not your job to address
    >> it. But it seems you were working on it.
    >
    > We are all working together here, so please refrain from telling
    > people what they should or should not be working on. (I am aware that
    > you probably did not mean it that way, but things tend to get lost in
    > translation very easily on the mailing list)

    Maybe I found the wrong words, sorry.

    Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
    --
    Everything you wanna know about Linux kernel regression tracking:
    https://linux-regtracking.leemhuis.info/about/#tldr
    If I did something stupid, please tell me, as explained on that page.

    \
     
     \ /
      Last update: 2023-03-27 00:37    [W:7.179 / U:0.056 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site