Messages in this thread | | | Subject | Re: [PATCH mm] vmalloc: back off when the current task is OOM-killed | From | Tetsuo Handa <> | Date | Mon, 20 Sep 2021 10:22:46 +0900 |
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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?
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