Messages in this thread | | | Subject | Re: [PATCH v12 1/9] hugetlb_cgroup: Add hugetlb_cgroup reservation counter | From | Mike Kravetz <> | Date | Tue, 18 Feb 2020 11:14:21 -0800 |
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On 2/18/20 10:35 AM, Mina Almasry wrote: > On Tue, Feb 18, 2020 at 6:21 AM Qian Cai <cai@lca.pw> wrote: >> >> On Tue, 2020-02-11 at 15:19 -0800, Andrew Morton wrote: >>> On Tue, 11 Feb 2020 13:31:20 -0800 Mina Almasry <almasrymina@google.com> wrote: >>> >> [ 7933.806377][T14355] ------------[ cut here ]------------ >> [ 7933.806541][T14355] kernel BUG at mm/hugetlb.c:490! >> VM_BUG_ON(t - f <= 1); >> [ 7933.806562][T14355] Oops: Exception in kernel mode, sig: 5 [#1] <snip> > Hi Qian, > > Yes this VM_BUG_ON was added by a patch in the series ("hugetlb: > disable region_add file_region coalescing") so it's definitely related > to the series. I'm taking a look at why this VM_BUG_ON fires. Can you > confirm you reproduce this by running hugemmap06 from the ltp on a > powerpc machine? Can I maybe have your config? > > Thanks!
Hi Mina,
Looking at the region_chg code again, we do a
resv->adds_in_progress += *out_regions_needed;
and then potentially drop the lock to allocate the needed entries. Could anopther thread (only adding reservation for a single page) then come in and notice that there are not enough entries in the cache and hit the VM_BUG_ON()?
-- Mike Kravetz
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