diff options
author | Hugh Dickins <hughd@google.com> | 2021-06-24 18:39:52 -0700 |
---|---|---|
committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-07-11 12:46:40 +0200 |
commit | c52e6f64804267cc8c9f26ab41588eeeae6fb9a7 (patch) | |
tree | 1c560e7f956adae62b7f2f45b9b64fa3cbfa4bcf /include/linux | |
parent | 07cc82b921bc60194bdc4a2ccea7d69f2d789348 (diff) | |
download | linux-stable-c52e6f64804267cc8c9f26ab41588eeeae6fb9a7.tar.gz linux-stable-c52e6f64804267cc8c9f26ab41588eeeae6fb9a7.tar.bz2 linux-stable-c52e6f64804267cc8c9f26ab41588eeeae6fb9a7.zip |
mm, futex: fix shared futex pgoff on shmem huge page
[ Upstream commit fe19bd3dae3d15d2fbfdb3de8839a6ea0fe94264 ]
If more than one futex is placed on a shmem huge page, it can happen
that waking the second wakes the first instead, and leaves the second
waiting: the key's shared.pgoff is wrong.
When 3.11 commit 13d60f4b6ab5 ("futex: Take hugepages into account when
generating futex_key"), the only shared huge pages came from hugetlbfs,
and the code added to deal with its exceptional page->index was put into
hugetlb source. Then that was missed when 4.8 added shmem huge pages.
page_to_pgoff() is what others use for this nowadays: except that, as
currently written, it gives the right answer on hugetlbfs head, but
nonsense on hugetlbfs tails. Fix that by calling hugetlbfs-specific
hugetlb_basepage_index() on PageHuge tails as well as on head.
Yes, it's unconventional to declare hugetlb_basepage_index() there in
pagemap.h, rather than in hugetlb.h; but I do not expect anything but
page_to_pgoff() ever to need it.
[akpm@linux-foundation.org: give hugetlb_basepage_index() prototype the correct scope]
Link: https://lkml.kernel.org/r/b17d946b-d09-326e-b42a-52884c36df32@google.com
Fixes: 800d8c63b2e9 ("shmem: add huge pages support")
Reported-by: Neel Natu <neelnatu@google.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Zhang Yi <wetpzy@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Darren Hart <dvhart@infradead.org>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Note on stable backport: leave redundant #include <linux/hugetlb.h>
in kernel/futex.c, to avoid conflict over the header files included.
Resolved trivial conflicts in include/linux/hugetlb.h.
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'include/linux')
-rw-r--r-- | include/linux/hugetlb.h | 15 | ||||
-rw-r--r-- | include/linux/pagemap.h | 13 |
2 files changed, 7 insertions, 21 deletions
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 8dd365c65478..6417bc845db5 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -451,17 +451,6 @@ static inline int hstate_index(struct hstate *h) return h - hstates; } -pgoff_t __basepage_index(struct page *page); - -/* Return page->index in PAGE_SIZE units */ -static inline pgoff_t basepage_index(struct page *page) -{ - if (!PageCompound(page)) - return page->index; - - return __basepage_index(page); -} - extern int dissolve_free_huge_pages(unsigned long start_pfn, unsigned long end_pfn); static inline bool hugepage_migration_supported(struct hstate *h) @@ -529,10 +518,6 @@ static inline unsigned int pages_per_huge_page(struct hstate *h) #define hstate_index_to_shift(index) 0 #define hstate_index(h) 0 -static inline pgoff_t basepage_index(struct page *page) -{ - return page->index; -} #define dissolve_free_huge_pages(s, e) 0 #define hugepage_migration_supported(h) false diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h index 35f4c4d9c405..8672291633dd 100644 --- a/include/linux/pagemap.h +++ b/include/linux/pagemap.h @@ -374,7 +374,7 @@ static inline struct page *read_mapping_page(struct address_space *mapping, } /* - * Get index of the page with in radix-tree + * Get index of the page within radix-tree (but not for hugetlb pages). * (TODO: remove once hugetlb pages will have ->index in PAGE_SIZE) */ static inline pgoff_t page_to_index(struct page *page) @@ -393,15 +393,16 @@ static inline pgoff_t page_to_index(struct page *page) return pgoff; } +extern pgoff_t hugetlb_basepage_index(struct page *page); + /* - * Get the offset in PAGE_SIZE. - * (TODO: hugepage should have ->index in PAGE_SIZE) + * Get the offset in PAGE_SIZE (even for hugetlb pages). + * (TODO: hugetlb pages should have ->index in PAGE_SIZE) */ static inline pgoff_t page_to_pgoff(struct page *page) { - if (unlikely(PageHeadHuge(page))) - return page->index << compound_order(page); - + if (unlikely(PageHuge(page))) + return hugetlb_basepage_index(page); return page_to_index(page); } |