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mm: gup: fix potential pgmap refcnt leak in __gup_device_huge() 

When failed to try_grab_page, put_dev_pagemap() is missed.  So pgmap
refcnt will leak in this case.  Also we remove the check for pgmap against
NULL as it's also checked inside the put_dev_pagemap().

[akpm@linux-foundation.org: simplify, cleanup]
[akpm@linux-foundation.org: fix return value]

Link: https://lkml.kernel.org/r/20210807093620.21347-5-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Fixes: 3faa52c03f ("mm/gup: track FOLL_PIN pages")
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Reviewed-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Miaohe Lin 2021-09-02 14:53:42 -07:00 committed by Linus Torvalds
parent 06a9e69663
commit 6401c4eb57
1 changed files with 7 additions and 5 deletions
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12
mm/gup.c
View File

@ -2240,6 +2240,7 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
{
int nr_start = *nr;
struct dev_pagemap *pgmap = NULL;
int ret = 1;
do {
struct page *page = pfn_to_page(pfn);
@ -2247,21 +2248,22 @@ static int __gup_device_huge(unsigned long pfn, unsigned long addr,
pgmap = get_dev_pagemap(pfn, pgmap);
if (unlikely(!pgmap)) {
undo_dev_pagemap(nr, nr_start, flags, pages);
return 0;
ret = 0;
break;
}
SetPageReferenced(page);
pages[*nr] = page;
if (unlikely(!try_grab_page(page, flags))) {
undo_dev_pagemap(nr, nr_start, flags, pages);
return 0;
ret = 0;
break;
}
(*nr)++;
pfn++;
} while (addr += PAGE_SIZE, addr != end);
if (pgmap)
put_dev_pagemap(pgmap);
return 1;
put_dev_pagemap(pgmap);
return ret;
}
static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr,