Messages in this thread | | | From | Daniel Vacek <> | Date | Sat, 3 Mar 2018 02:08:27 +0100 | Subject | Re: [PATCH v3 2/2] mm/page_alloc: fix memmap_init_zone pageblock alignment |
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On Sat, Mar 3, 2018 at 1:40 AM, Andrew Morton <akpm@linux-foundation.org> wrote: > On Sat, 3 Mar 2018 01:12:26 +0100 Daniel Vacek <neelx@redhat.com> wrote: > >> Commit b92df1de5d28 ("mm: page_alloc: skip over regions of invalid pfns >> where possible") introduced a bug where move_freepages() triggers a >> VM_BUG_ON() on uninitialized page structure due to pageblock alignment. > > b92df1de5d28 was merged a year ago. Can you suggest why this hasn't > been reported before now?
Yeah. I was surprised myself I couldn't find a fix to backport to RHEL. But actually customers started to report this as soon as 7.4 (where b92df1de5d28 was merged in RHEL) was released. I remember reports from September/October-ish times. It's not easily reproduced and happens on a handful of machines only. I guess that's why. But that does not make it less serious, I think.
Though there actually is a report here: https://bugzilla.kernel.org/show_bug.cgi?id=196443
And there are reports for Fedora from July: https://bugzilla.redhat.com/show_bug.cgi?id=1473242 and CentOS: https://bugs.centos.org/view.php?id=13964 and we internally track several dozens reports for RHEL bug https://bugzilla.redhat.com/show_bug.cgi?id=1525121
Enough? ;-)
> This makes me wonder whether a -stable backport is really needed...
For some machines it definitely is. Won't hurt either, IMHO.
--nX
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