On Mon, Jan 12, 2015 at 11:21 PM, Andrew Morton <a...@linux-foundation.org> wrote: > On Sun, 11 Jan 2015 16:54:06 +0300 Konstantin Khlebnikov <koc...@gmail.com> > wrote: > >> Fix for BUG_ON(anon_vma->degree) splashes in unlink_anon_vmas() >> ("kernel BUG at mm/rmap.c:399!"). >> >> Anon_vma_clone() is usually called for a copy of source vma in destination >> argument. If source vma has anon_vma it should be already in dst->anon_vma. >> NULL in dst->anon_vma is used as a sign that it's called from >> anon_vma_fork(). >> In this case anon_vma_clone() finds anon_vma for reusing. >> >> Vma_adjust() calls it differently and this breaks anon_vma reusing logic: >> anon_vma_clone() links vma to old anon_vma and updates degree counters but >> vma_adjust() overrides vma->anon_vma right after that. As a result final >> unlink_anon_vmas() decrements degree for wrong anon_vma. >> >> This patch assigns ->anon_vma before calling anon_vma_clone(). >> >> Signed-off-by: Konstantin Khlebnikov <koc...@gmail.com> >> Fixes: 7a3ef208e662 ("mm: prevent endless growth of anon_vma hierarchy") > > I've asked Greg not to take 7a3ef208e662 into -stable because of this > problem. So if you still think we should fix this in -stable, could > you please prepare an updated patch and send it to Greg?
Will do. But let's wait for some just to be sure that is the last bug here. > >> Tested-by: Chris Clayton <chris2...@googlemail.com> >> Tested-by: Oded Gabbay <oded.gab...@amd.com> >> Cc: Daniel Forrest <dan.forr...@ssec.wisc.edu> >> Cc: Michal Hocko <mho...@suse.cz> >> Cc: Rik van Riel <r...@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/