lkml.org 
[lkml]   [2021]   [Sep]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH mm] vmalloc: back off when the current task is OOM-killed
    From
    Date
    On 2021/09/20 8:31, Andrew Morton wrote:
    > On Fri, 17 Sep 2021 11:06:49 +0300 Vasily Averin <vvs@virtuozzo.com> wrote:
    >
    >> Huge vmalloc allocation on heavy loaded node can lead to a global
    >> memory shortage. A task called vmalloc can have the worst badness
    >> and be chosen by OOM-killer, however received fatal signal and
    >> oom victim mark does not interrupt allocation cycle. Vmalloc will
    >> continue allocating pages over and over again, exacerbating the crisis
    >> and consuming the memory freed up by another killed tasks.
    >>
    >> This patch allows OOM-killer to break vmalloc cycle, makes OOM more
    >> effective and avoid host panic.
    >>
    >> Unfortunately it is not 100% safe. Previous attempt to break vmalloc
    >> cycle was reverted by commit b8c8a338f75e ("Revert "vmalloc: back off when
    >> the current task is killed"") due to some vmalloc callers did not handled
    >> failures properly. Found issues was resolved, however, there may
    >> be other similar places.
    >
    > Well that was lame of us.
    >
    > I believe that at least one of the kernel testbots can utilize fault
    > injection. If we were to wire up vmalloc (as we have done with slab
    > and pagealloc) then this will help to locate such buggy vmalloc callers.

    __alloc_pages_bulk() has three callers.

    alloc_pages_bulk_list() => No in-tree users.

    alloc_pages_bulk_array() => Used by xfs_buf_alloc_pages(), __page_pool_alloc_pages_slow(), svc_alloc_arg().

    xfs_buf_alloc_pages() => Might retry forever until all pages are allocated (i.e. effectively __GFP_NOFAIL). This patch can cause infinite loop problem.

    __page_pool_alloc_pages_slow() => Will not retry if allocation failed. This patch might help.

    svc_alloc_arg() => Will not retry if signal pending. This patch might help only if allocating a lot of pages.

    alloc_pages_bulk_array_node() => Used by vm_area_alloc_pages().

    vm_area_alloc_pages() => Used by __vmalloc_area_node() from __vmalloc_node_range() from vmalloc functions. Needs !__GFP_NOFAIL check?

    \
     
     \ /
      Last update: 2021-09-20 03:24    [W:2.796 / U:0.004 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site