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authorKairui Song <kasong@tencent.com>2022-12-19 21:58:40 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-01-19 04:12:45 +0300
commitcbc2bd98db85504074c1b94175e5e136e457dc0b (patch)
tree67775d3bb34faee300c78a1e88c82e366956f2f3 /mm/swap_state.c
parent16ba391e9c6bc26e6f0c950f2117f57b8e542d71 (diff)
downloadlinux-cbc2bd98db85504074c1b94175e5e136e457dc0b.tar.xz
swap: avoid holding swap reference in swap_cache_get_folio
All its callers either already hold a reference to, or lock the swap device while calling this function. There is only one exception in shmem_swapin_folio, just make this caller also hold a reference of the swap device, so this helper can be simplified and saves a few cycles. This also provides finer control of error handling in shmem_swapin_folio, on race (with swap off), it can just try again. For invalid swap entry, it can fail with a proper error code. Link: https://lkml.kernel.org/r/20221219185840.25441-5-ryncsn@gmail.com Signed-off-by: Kairui Song <kasong@tencent.com> Cc: David Hildenbrand <david@redhat.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox (Oracle) <willy@infradead.org> Cc: Miaohe Lin <linmiaohe@huawei.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/swap_state.c')
-rw-r--r--mm/swap_state.c8
1 files changed, 2 insertions, 6 deletions
diff --git a/mm/swap_state.c b/mm/swap_state.c
index d8d171195a3a..cb9aaa00951d 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -321,19 +321,15 @@ static inline bool swap_use_vma_readahead(void)
* unlocked and with its refcount incremented - we rely on the kernel
* lock getting page table operations atomic even if we drop the folio
* lock before returning.
+ *
+ * Caller must lock the swap device or hold a reference to keep it valid.
*/
struct folio *swap_cache_get_folio(swp_entry_t entry,
struct vm_area_struct *vma, unsigned long addr)
{
struct folio *folio;
- struct swap_info_struct *si;
- si = get_swap_device(entry);
- if (!si)
- return NULL;
folio = filemap_get_folio(swap_address_space(entry), swp_offset(entry));
- put_swap_device(si);
-
if (folio) {
bool vma_ra = swap_use_vma_readahead();
bool readahead;