Messages in this thread Patch in this message | | | Subject | [RFC][PATCH 1/2] hugetlb: fix resv_map leak in error path | From | Dave Hansen <> | Date | Mon, 21 May 2012 13:30:22 -0700 |
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When called for anonymous (non-shared) mappings, hugetlb_reserve_pages() does a resv_map_alloc(). It depends on code in hugetlbfs's vm_ops->close() to release that allocation.
However, in the mmap() failure path, we do a plain unmap_region() without the remove_vma() which actually calls vm_ops->close().
This is a decent fix. This leak could get reintroduced if new code (say, after hugetlb_reserve_pages() in hugetlbfs_file_mmap()) decides to return an error. But, I think it would have to unroll the reservation anyway.
This hasn't been extensively tested. Pretty much compile and boot tested along with Christoph's test case:
http://marc.info/?l=linux-mm&m=133728900729735
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com> Acked-by: Mel Gorman <mel@csn.ul.ie> ecked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reported/tested-by: Christoph Lameter <cl@linux.com>
---
linux-2.6.git-dave/mm/hugetlb.c | 28 ++++++++++++++++++++++------ 1 file changed, 22 insertions(+), 6 deletions(-)
diff -puN mm/hugetlb.c~hugetlb-fix-leak mm/hugetlb.c --- linux-2.6.git/mm/hugetlb.c~hugetlb-fix-leak 2012-05-21 13:24:38.369857759 -0700 +++ linux-2.6.git-dave/mm/hugetlb.c 2012-05-21 13:24:38.377857849 -0700 @@ -2157,6 +2157,15 @@ static void hugetlb_vm_op_open(struct vm kref_get(&reservations->refs); } +static void resv_map_put(struct vm_area_struct *vma) +{ + struct resv_map *reservations = vma_resv_map(vma); + + if (!reservations) + return; + kref_put(&reservations->refs, resv_map_release); +} + static void hugetlb_vm_op_close(struct vm_area_struct *vma) { struct hstate *h = hstate_vma(vma); @@ -2173,7 +2182,7 @@ static void hugetlb_vm_op_close(struct v reserve = (end - start) - region_count(&reservations->regions, start, end); - kref_put(&reservations->refs, resv_map_release); + resv_map_put(vma); if (reserve) { hugetlb_acct_memory(h, -reserve); @@ -2990,12 +2999,16 @@ int hugetlb_reserve_pages(struct inode * set_vma_resv_flags(vma, HPAGE_RESV_OWNER); } - if (chg < 0) - return chg; + if (chg < 0) { + ret = chg; + goto out_err; + } /* There must be enough pages in the subpool for the mapping */ - if (hugepage_subpool_get_pages(spool, chg)) - return -ENOSPC; + if (hugepage_subpool_get_pages(spool, chg)) { + ret = -ENOSPC; + goto out_err; + } /* * Check enough hugepages are available for the reservation. @@ -3004,7 +3017,7 @@ int hugetlb_reserve_pages(struct inode * ret = hugetlb_acct_memory(h, chg); if (ret < 0) { hugepage_subpool_put_pages(spool, chg); - return ret; + goto out_err; } /* @@ -3021,6 +3034,9 @@ int hugetlb_reserve_pages(struct inode * if (!vma || vma->vm_flags & VM_MAYSHARE) region_add(&inode->i_mapping->private_list, from, to); return 0; +out_err: + resv_map_put(vma); + return ret; } void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed) diff -puN Documentation/stable_kernel_rules.txt~hugetlb-fix-leak Documentation/stable_kernel_rules.txt _
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