The patch titled Subject: mm/mempolicy.c: do not put mempolicy before using its nodemask has been added to the -mm tree. Its filename is mm-mempolicyc-do-not-put-mempolicy-before-using-its-nodemask.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-mempolicyc-do-not-put-mempolicy-before-using-its-nodemask.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-mempolicyc-do-not-put-mempolicy-before-using-its-nodemask.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Vlastimil Babka <vbabka@xxxxxxx> Subject: mm/mempolicy.c: do not put mempolicy before using its nodemask Since commit be97a41b291e ("mm/mempolicy.c: merge alloc_hugepage_vma to alloc_pages_vma") alloc_pages_vma() can potentially free a mempolicy by mpol_cond_put() before accessing the embedded nodemask by __alloc_pages_nodemask(). The commit log says it's so "we can use a single exit path within the function" but that's clearly wrong. We can still do that when doing mpol_cond_put() after the allocation attempt. Make sure the mempolicy is not freed prematurely, otherwise __alloc_pages_nodemask() can end up using a bogus nodemask, which could lead e.g. to premature OOM. Fixes: be97a41b291e ("mm/mempolicy.c: merge alloc_hugepage_vma to alloc_pages_vma") Link: http://lkml.kernel.org/r/20170118141124.8345-1-vbabka@xxxxxxx Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> Acked-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxxx> Acked-by: David Rientjes <rientjes@xxxxxxxxxx> Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx> Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> [4.0+] Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/mempolicy.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff -puN mm/mempolicy.c~mm-mempolicyc-do-not-put-mempolicy-before-using-its-nodemask mm/mempolicy.c --- a/mm/mempolicy.c~mm-mempolicyc-do-not-put-mempolicy-before-using-its-nodemask +++ a/mm/mempolicy.c @@ -2017,8 +2017,8 @@ retry_cpuset: nmask = policy_nodemask(gfp, pol); zl = policy_zonelist(gfp, pol, node); - mpol_cond_put(pol); page = __alloc_pages_nodemask(gfp, order, zl, nmask); + mpol_cond_put(pol); out: if (unlikely(!page && read_mems_allowed_retry(cpuset_mems_cookie))) goto retry_cpuset; _ Patches currently in -mm which might be from vbabka@xxxxxxx are mm-mempolicyc-do-not-put-mempolicy-before-using-its-nodemask.patch mm-page_alloc-dont-convert-pfn-to-idx-when-merging.patch mm-page_alloc-avoid-page_to_pfn-when-merging-buddies.patch mm-page_alloc-convert-page_group_by_mobility_disable-to-static-key.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html