From: Roman Gushchin guro@fb.com
mainline inclusion from mainline-v5.14-rc1 commit 8ea2e1e35d1eb4c76290ff5d565a1bfd6c24f117 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/I4BE79 CVE: NA
------------------------------------------------- Factor out the pcpu_check_block_hint() helper, which will be useful in the future. The new function checks if the allocation can likely fit within the contig hint.
Signed-off-by: Roman Gushchin guro@fb.com Signed-off-by: Dennis Zhou dennis@kernel.org Signed-off-by: Dennis Zhou dennis@kernel.org (cherry picked from commit 8ea2e1e35d1eb4c76290ff5d565a1bfd6c24f117) Signed-off-by: Yuanzheng Song songyuanzheng@huawei.com Reviewed-by: Kefeng Wang wangkefeng.wang@huawei.com Signed-off-by: Zheng Zengkai zhengzengkai@huawei.com --- mm/percpu.c | 30 +++++++++++++++++++++++------- 1 file changed, 23 insertions(+), 7 deletions(-)
diff --git a/mm/percpu.c b/mm/percpu.c index da0567ab3459..dd4e31934f3e 100644 --- a/mm/percpu.c +++ b/mm/percpu.c @@ -305,6 +305,25 @@ static unsigned long pcpu_block_off_to_off(int index, int off) return index * PCPU_BITMAP_BLOCK_BITS + off; }
+/** + * pcpu_check_block_hint - check against the contig hint + * @block: block of interest + * @bits: size of allocation + * @align: alignment of area (max PAGE_SIZE) + * + * Check to see if the allocation can fit in the block's contig hint. + * Note, a chunk uses the same hints as a block so this can also check against + * the chunk's contig hint. + */ +static bool pcpu_check_block_hint(struct pcpu_block_md *block, int bits, + size_t align) +{ + int bit_off = ALIGN(block->contig_hint_start, align) - + block->contig_hint_start; + + return bit_off + bits <= block->contig_hint; +} + /* * pcpu_next_hint - determine which hint to use * @block: block of interest @@ -1065,14 +1084,11 @@ static int pcpu_find_block_fit(struct pcpu_chunk *chunk, int alloc_bits, int bit_off, bits, next_off;
/* - * Check to see if the allocation can fit in the chunk's contig hint. - * This is an optimization to prevent scanning by assuming if it - * cannot fit in the global hint, there is memory pressure and creating - * a new chunk would happen soon. + * This is an optimization to prevent scanning by assuming if the + * allocation cannot fit in the global hint, there is memory pressure + * and creating a new chunk would happen soon. */ - bit_off = ALIGN(chunk_md->contig_hint_start, align) - - chunk_md->contig_hint_start; - if (bit_off + alloc_bits > chunk_md->contig_hint) + if (!pcpu_check_block_hint(chunk_md, alloc_bits, align)) return -1;
bit_off = pcpu_next_hint(chunk_md, alloc_bits);