| Date | Sat, 9 Jun 2012 11:44:44 +0200 | From | Johannes Weiner <> | Subject | Re: [PATCH -V8 05/16] hugetlb: avoid taking i_mmap_mutex in unmap_single_vma() for hugetlb |
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On Sat, Jun 09, 2012 at 02:29:50PM +0530, Aneesh Kumar K.V wrote: > From: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com> > > i_mmap_mutex lock was added in unmap_single_vma by 502717f4e ("hugetlb: > fix linked list corruption in unmap_hugepage_range()") but we don't use > page->lru in unmap_hugepage_range any more. Also the lock was taken > higher up in the stack in some code path. That would result in deadlock. > > unmap_mapping_range (i_mmap_mutex) > -> unmap_mapping_range_tree > -> unmap_mapping_range_vma > -> zap_page_range_single > -> unmap_single_vma > -> unmap_hugepage_range (i_mmap_mutex) > > For shared pagetable support for huge pages, since pagetable pages are ref > counted we don't need any lock during huge_pmd_unshare. We do take > i_mmap_mutex in huge_pmd_share while walking the vma_prio_tree in mapping. > (39dde65c9940c97f ("shared page table for hugetlb page")). > > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
This patch (together with the previous one) seems like a bugfix that's not really related to the hugetlb controller, unless I miss something.
Could you please submit the fix separately?
Maybe also fold the two patches into one and make it a single bugfix change that gets rid of the lock by switching away from page->lru.
Thanks
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