hugetlb: ensure we do not reference a surplus page after handing it to buddy
Subsystems (2)
PATCH 1/1 hugetlb: ensure we do not reference a surplus page after handing it to buddy
When we free a page via free_huge_page and we detect that we are in surplus the page will be returned to the buddy. After this we no longer own the page. However at the end free_huge_page we clear out our mapping pointer from page private. Even where the page is not a surplus we free the page to the hugepage pool, drop the pool locks and then clear page private. In either case the page may have been reallocated. BAD.
Make sure we clear out page private before we free the page.
--- mm/hugetlb.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
mm/hugetlb.c +1 -1
@@ -120,6 +120,7 @@ static void free_huge_page(struct page *page)struct address_space *mapping; mapping = (struct address_space *)page_private (page); +set_page_private (page,0 );BUG_ON (page_count (page));INIT_LIST_HEAD (&page->lru);
@@ -134,7 +135,6 @@ static void free_huge_page(struct page *page)spin_unlock (&hugetlb_lock);if (mapping)hugetlb_put_quota (mapping,1 ); -set_page_private (page,0 ); }/*
Indeed. I'll take credit for this thinko...
Quoted 10 lines · Andy Whitcroft
When we free a page via
free_huge_pageand we detect that we are in surplus the page will be returned to the buddy. After this we no longer own the page. However at the endfree_huge_pagewe clear out our mapping pointer from page private. Even where the page is not a surplus we free the page to the hugepage pool, drop the pool locks and then clear page private. In either case the page may have been reallocated. BAD.Make sure we clear out page private before we free the page.
Signed-off-by Andy Whitcroft <[email protected]>
Signature · 8 lines
Adam Litke - (agl at us.ibm.com) IBM Linux Technology Center -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"[email protected]"> [email protected] </a>
Andrew Morton
maintainerQuoted 10 lines · On Tue, 19 Feb 2008 12:41:51 -0600 Adam Litke <[email protected]> wrote:
Indeed. I'll take credit for this thinko...
Quoted 7 lines · Andy Whitcroft
When we free a page via
free_huge_pageand we detect that we are in surplus the page will be returned to the buddy. After this we no longer own the page. However at the endfree_huge_pagewe clear out our mapping pointer from page private. Even where the page is not a surplus we free the page to the hugepage pool, drop the pool locks and then clear page private. In either case the page may have been reallocated. BAD.
Quoted 5 lines
Quoted 3 lines
Make sure we clear out page private before we free the page.
Signed-off-by Andy Whitcroft <[email protected]>Acked-by Adam Litke <[email protected]>
Was I right to assume that this is also needed in 2.6.24.x?
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To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to [email protected]. For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"[email protected]"> [email protected] </a>
Quoted 12 lines · Andrew Morton
Quoted 10 lines · On Tue, 19 Feb 2008 12:41:51 -0600 Adam Litke <[email protected]> wrote:
Indeed. I'll take credit for this thinko...
Quoted 7 lines · Andy Whitcroft
When we free a page via
free_huge_pageand we detect that we are in surplus the page will be returned to the buddy. After this we no longer own the page. However at the endfree_huge_pagewe clear out our mapping pointer from page private. Even where the page is not a surplus we free the page to the hugepage pool, drop the pool locks and then clear page private. In either case the page may have been reallocated. BAD.
Quoted 7 lines
Quoted 5 lines
Quoted 3 lines
Make sure we clear out page private before we free the page.
Signed-off-by Andy Whitcroft <[email protected]>Acked-by Adam Litke <[email protected]>Was I right to assume that this is also needed in 2.6.24.x?
Yep. Thanks Andrew.
Signature · 2 lines
Adam Litke - (agl at us.ibm.com) IBM Linux Technology Center