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Baolin Wangakpm00
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mm: shmem: avoid allocating huge pages larger than MAX_PAGECACHE_ORDER for shmem
Similar to commit d659b71 ("mm/huge_memory: avoid PMD-size page cache if needed"), ARM64 can support 512MB PMD-sized THP when the base page size is 64KB, which is larger than the maximum supported page cache size MAX_PAGECACHE_ORDER. This is not expected. To fix this issue, use THP_ORDERS_ALL_FILE_DEFAULT for shmem to filter allowable huge orders. [baolin.wang@linux.alibaba.com: remove comment, per Barry] Link: https://lkml.kernel.org/r/c55d7ef7-78aa-4ed6-b897-c3e03a3f3ab7@linux.alibaba.com [wangkefeng.wang@huawei.com: remove local `orders'] Link: https://lkml.kernel.org/r/87769ae8-b6c6-4454-925d-1864364af9c8@huawei.com Link: https://lkml.kernel.org/r/117121665254442c3c7f585248296495e5e2b45c.1722404078.git.baolin.wang@linux.alibaba.com Fixes: e7a2ab7 ("mm: shmem: add mTHP support for anonymous shmem") Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com> Reviewed-by: Barry Song <baohua@kernel.org> Cc: Barry Song <21cnbao@gmail.com> Cc: David Hildenbrand <david@redhat.com> Cc: Gavin Shan <gshan@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Lance Yang <ioworker0@gmail.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Zi Yan <ziy@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Lines changed: 1 addition & 6 deletions

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mm/shmem.c

Lines changed: 1 addition & 6 deletions
Original file line numberDiff line numberDiff line change
@@ -1629,11 +1629,6 @@ unsigned long shmem_allowable_huge_orders(struct inode *inode,
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unsigned long mask = READ_ONCE(huge_shmem_orders_always);
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unsigned long within_size_orders = READ_ONCE(huge_shmem_orders_within_size);
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unsigned long vm_flags = vma->vm_flags;
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/*
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* Check all the (large) orders below HPAGE_PMD_ORDER + 1 that
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* are enabled for this vma.
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*/
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unsigned long orders = BIT(PMD_ORDER + 1) - 1;
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loff_t i_size;
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int order;
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@@ -1678,7 +1673,7 @@ unsigned long shmem_allowable_huge_orders(struct inode *inode,
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if (global_huge)
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mask |= READ_ONCE(huge_shmem_orders_inherit);
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return orders & mask;
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return THP_ORDERS_ALL_FILE_DEFAULT & mask;
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}
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static unsigned long shmem_suitable_orders(struct inode *inode, struct vm_fault *vmf,

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