The patch titled Subject: tmpfs: fix shared mempolicy leak has been added to the -mm tree. Its filename is tmpfs-fix-shared-mempolicy-leak.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: Mel Gorman <mgorman@xxxxxxx> Subject: tmpfs: fix shared mempolicy leak This fixes a regression in 3.7-rc, which has since gone into stable. Commit 00442ad04a5e ("mempolicy: fix a memory corruption by refcount imbalance in alloc_pages_vma()") changed get_vma_policy() to raise the refcount on a shmem shared mempolicy; whereas shmem_alloc_page() went on expecting alloc_page_vma() to drop the refcount it had acquired. This deserves a rework: but for now fix the leak in shmem_alloc_page(). Hugh: shmem_swapin() did not need a fix, but surely it's clearer to use the same refcounting there as in shmem_alloc_page(), delete its onstack mempolicy, and the strange mpol_cond_copy() and __mpol_cond_copy() - those were invented to let swapin_readahead() make an unknown number of calls to alloc_pages_vma() with one mempolicy; but since 00442ad04a5e, alloc_pages_vma() has kept refcount in balance, so now no problem. Reported-and-tested-by: Tommi Rantala <tt.rantala@xxxxxxxxx> Signed-off-by: Mel Gorman <mgorman@xxxxxxx> Signed-off-by: Hugh Dickins <hughd@xxxxxxxxxx> Tested-by: Tommi Rantala <tt.rantala@xxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- include/linux/mempolicy.h | 16 ---------------- mm/mempolicy.c | 22 ---------------------- mm/shmem.c | 26 ++++++++++++++++---------- 3 files changed, 16 insertions(+), 48 deletions(-) diff -puN include/linux/mempolicy.h~tmpfs-fix-shared-mempolicy-leak include/linux/mempolicy.h --- a/include/linux/mempolicy.h~tmpfs-fix-shared-mempolicy-leak +++ a/include/linux/mempolicy.h @@ -82,16 +82,6 @@ static inline void mpol_cond_put(struct __mpol_put(pol); } -extern struct mempolicy *__mpol_cond_copy(struct mempolicy *tompol, - struct mempolicy *frompol); -static inline struct mempolicy *mpol_cond_copy(struct mempolicy *tompol, - struct mempolicy *frompol) -{ - if (!frompol) - return frompol; - return __mpol_cond_copy(tompol, frompol); -} - extern struct mempolicy *__mpol_dup(struct mempolicy *pol); static inline struct mempolicy *mpol_dup(struct mempolicy *pol) { @@ -215,12 +205,6 @@ static inline void mpol_cond_put(struct { } -static inline struct mempolicy *mpol_cond_copy(struct mempolicy *to, - struct mempolicy *from) -{ - return from; -} - static inline void mpol_get(struct mempolicy *pol) { } diff -puN mm/mempolicy.c~tmpfs-fix-shared-mempolicy-leak mm/mempolicy.c --- a/mm/mempolicy.c~tmpfs-fix-shared-mempolicy-leak +++ a/mm/mempolicy.c @@ -2037,28 +2037,6 @@ struct mempolicy *__mpol_dup(struct memp return new; } -/* - * If *frompol needs [has] an extra ref, copy *frompol to *tompol , - * eliminate the * MPOL_F_* flags that require conditional ref and - * [NOTE!!!] drop the extra ref. Not safe to reference *frompol directly - * after return. Use the returned value. - * - * Allows use of a mempolicy for, e.g., multiple allocations with a single - * policy lookup, even if the policy needs/has extra ref on lookup. - * shmem_readahead needs this. - */ -struct mempolicy *__mpol_cond_copy(struct mempolicy *tompol, - struct mempolicy *frompol) -{ - if (!mpol_needs_cond_ref(frompol)) - return frompol; - - *tompol = *frompol; - tompol->flags &= ~MPOL_F_SHARED; /* copy doesn't need unref */ - __mpol_put(frompol); - return tompol; -} - /* Slow path of a mempolicy comparison */ bool __mpol_equal(struct mempolicy *a, struct mempolicy *b) { diff -puN mm/shmem.c~tmpfs-fix-shared-mempolicy-leak mm/shmem.c --- a/mm/shmem.c~tmpfs-fix-shared-mempolicy-leak +++ a/mm/shmem.c @@ -910,25 +910,29 @@ static struct mempolicy *shmem_get_sbmpo static struct page *shmem_swapin(swp_entry_t swap, gfp_t gfp, struct shmem_inode_info *info, pgoff_t index) { - struct mempolicy mpol, *spol; struct vm_area_struct pvma; - - spol = mpol_cond_copy(&mpol, - mpol_shared_policy_lookup(&info->policy, index)); + struct page *page; /* Create a pseudo vma that just contains the policy */ pvma.vm_start = 0; /* Bias interleave by inode number to distribute better across nodes */ pvma.vm_pgoff = index + info->vfs_inode.i_ino; pvma.vm_ops = NULL; - pvma.vm_policy = spol; - return swapin_readahead(swap, gfp, &pvma, 0); + pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); + + page = swapin_readahead(swap, gfp, &pvma, 0); + + /* Drop reference taken by mpol_shared_policy_lookup() */ + mpol_cond_put(pvma.vm_policy); + + return page; } static struct page *shmem_alloc_page(gfp_t gfp, struct shmem_inode_info *info, pgoff_t index) { struct vm_area_struct pvma; + struct page *page; /* Create a pseudo vma that just contains the policy */ pvma.vm_start = 0; @@ -937,10 +941,12 @@ static struct page *shmem_alloc_page(gfp pvma.vm_ops = NULL; pvma.vm_policy = mpol_shared_policy_lookup(&info->policy, index); - /* - * alloc_page_vma() will drop the shared policy reference - */ - return alloc_page_vma(gfp, &pvma, 0); + page = alloc_page_vma(gfp, &pvma, 0); + + /* Drop reference taken by mpol_shared_policy_lookup() */ + mpol_cond_put(pvma.vm_policy); + + return page; } #else /* !CONFIG_NUMA */ #ifdef CONFIG_TMPFS _ Patches currently in -mm which might be from mgorman@xxxxxxx are tmpfs-fix-shared-mempolicy-leak.patch linux-next.patch memory_hotplug-fix-possible-incorrect-node_states.patch slub-hotplug-ignore-unrelated-nodes-hot-adding-and-hot-removing.patch mm-add-comment-on-storage-key-dirty-bit-semantics.patch mm-refactor-reinsert-of-swap_info-in-sys_swapoff.patch mm-do-not-call-frontswap_init-during-swapoff.patch mm-memmap_init_zone-performance-improvement.patch mm-allocate-kernel-pages-to-the-right-memcg.patch mm-memory-hotplug-dynamic-configure-movable-memory-and-portion-memory.patch memory_hotplug-handle-empty-zone-when-online_movable-online_kernel.patch memory_hotplug-ensure-every-online-node-has-normal-memory.patch mm-compaction-fix-compiler-warning.patch mm-add-a-reminder-comment-for-__gfp_bits_shift.patch numa-add-config_movable_node-for-movable-dedicated-node.patch numa-add-config_movable_node-for-movable-dedicated-node-fix.patch memory_hotplug-allow-online-offline-memory-to-result-movable-node.patch mm-introduce-new-field-managed_pages-to-struct-zone.patch mm-provide-more-accurate-estimation-of-pages-occupied-by-memmap.patch mm-provide-more-accurate-estimation-of-pages-occupied-by-memmap-fix.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html