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swap, __read_swap_cache_async(): enlarge get/put_swap_device protection range 

This makes the function a little easier to be understood because we don't
need to consider swapoff.  And this makes it possible to remove
get/put_swap_device() calling in some functions called by
__read_swap_cache_async().

Link: https://lkml.kernel.org/r/20230529061355.125791-3-ying.huang@intel.com
Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Chris Li (Google) <chrisl@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Huang Ying 2023-05-29 14:13:52 +08:00 committed by Andrew Morton
parent f9f956b550
commit 46a774d3ea
1 changed files with 21 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
mm/swap_state.c
View File

@ -417,9 +417,13 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
{
struct swap_info_struct *si;
struct folio *folio;
struct page *page;
void *shadow = NULL;
*new_page_allocated = false;
si = get_swap_device(entry);
if (!si)
return NULL;
for (;;) {
int err;
@ -428,14 +432,12 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
* called after swap_cache_get_folio() failed, re-calling
* that would confuse statistics.
*/
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 (!IS_ERR(folio))
return folio_file_page(folio, swp_offset(entry));
if (!IS_ERR(folio)) {
page = folio_file_page(folio, swp_offset(entry));
goto got_page;
}
/*
* Just skip read ahead for unused swap slot.
@ -446,7 +448,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
* else swap_off will be aborted if we return NULL.
*/
if (!__swp_swapcount(entry) && swap_slot_cache_enabled)
return NULL;
goto fail_put_swap;
/*
* Get a new page to read into from swap. Allocate it now,
@ -455,7 +457,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
*/
folio = vma_alloc_folio(gfp_mask, 0, vma, addr, false);
if (!folio)
return NULL;
goto fail_put_swap;
/*
* Swap entry may have been freed since our caller observed it.
@ -466,7 +468,7 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
folio_put(folio);
if (err != -EEXIST)
return NULL;
goto fail_put_swap;
/*
* We might race against __delete_from_swap_cache(), and
@ -500,12 +502,17 @@ struct page *__read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
/* Caller will initiate read into locked folio */
folio_add_lru(folio);
*new_page_allocated = true;
return &folio->page;
page = &folio->page;
got_page:
put_swap_device(si);
return page;
fail_unlock:
put_swap_folio(folio, entry);
folio_unlock(folio);
folio_put(folio);
fail_put_swap:
put_swap_device(si);
return NULL;
}
@ -514,6 +521,10 @@ fail_unlock:
* and reading the disk if it is not already cached.
* A failure return means that either the page allocation failed or that
* the swap entry is no longer in use.
*
* get/put_swap_device() aren't needed to call this function, because
* __read_swap_cache_async() call them and swap_readpage() holds the
* swap cache folio lock.
*/
struct page *read_swap_cache_async(swp_entry_t entry, gfp_t gfp_mask,
struct vm_area_struct *vma,