The patch titled
Subject: mm/shmem: return head page from find_lock_entry
has been added to the -mm tree. Its filename is
mm-shmem-return-head-page-from-find_lock_entry.patch
This patch should soon appear at
https://ozlabs.org/~akpm/mmots/broken-out/mm-shmem-return-head-page-from-find_lock_entry.patch
and later at
https://ozlabs.org/~akpm/mmotm/broken-out/mm-shmem-return-head-page-from-find_lock_entry.patch
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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm/shmem: return head page from find_lock_entry
Convert shmem_getpage_gfp() (the only remaining caller of
find_lock_entry()) to cope with a head page being returned instead of
the subpage for the index.
Link: https://lkml.kernel.org/r/20200910183318.20139-8-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Alexey Dobriyan <adobriyan@xxxxxxxxx>
Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Matthew Auld <matthew.auld@xxxxxxxxx>
Cc: William Kucharski <william.kucharski@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/pagemap.h | 9 +++++++++
mm/filemap.c | 25 +++++++++++--------------
mm/shmem.c | 20 +++++++++-----------
3 files changed, 29 insertions(+), 25 deletions(-)
--- a/include/linux/pagemap.h~mm-shmem-return-head-page-from-find_lock_entry
+++ a/include/linux/pagemap.h
@@ -371,6 +371,15 @@ static inline struct page *grab_cache_pa
mapping_gfp_mask(mapping));
}
+/* Does this page contain this index? */
+static inline bool thp_contains(struct page *head, pgoff_t index)
+{
+ /* HugeTLBfs indexes the page cache in units of hpage_size */
+ if (PageHuge(head))
+ return head->index == index;
+ return page_index(head) == (index & ~(thp_nr_pages(head) - 1UL));
+}
+
/*
* Given the page we found in the page cache, return the page corresponding
* to this index in the file
--- a/mm/filemap.c~mm-shmem-return-head-page-from-find_lock_entry
+++ a/mm/filemap.c
@@ -1594,37 +1594,34 @@ out:
}
/**
- * find_lock_entry - locate, pin and lock a page cache entry
- * @mapping: the address_space to search
- * @offset: the page cache index
+ * find_lock_entry - Locate and lock a page cache entry.
+ * @mapping: The address_space to search.
+ * @index: The page cache index.
*
- * Looks up the page cache slot at @mapping & @offset. If there is a
- * page cache page, it is returned locked and with an increased
- * refcount.
+ * Looks up the page at @mapping & @index. If there is a page in the
+ * cache, the head page is returned locked and with an increased refcount.
*
* If the slot holds a shadow entry of a previously evicted page, or a
* swap entry from shmem/tmpfs, it is returned.
*
- * find_lock_entry() may sleep.
- *
- * Return: the found page or shadow entry, %NULL if nothing is found.
+ * Context: May sleep.
+ * Return: The head page or shadow entry, %NULL if nothing is found.
*/
-struct page *find_lock_entry(struct address_space *mapping, pgoff_t offset)
+struct page *find_lock_entry(struct address_space *mapping, pgoff_t index)
{
struct page *page;
repeat:
- page = find_get_entry(mapping, offset);
+ page = find_get_entry(mapping, index);
if (page && !xa_is_value(page)) {
lock_page(page);
/* Has the page been truncated? */
- if (unlikely(page_mapping(page) != mapping)) {
+ if (unlikely(page->mapping != mapping)) {
unlock_page(page);
put_page(page);
goto repeat;
}
- page = find_subpage(page, offset);
- VM_BUG_ON_PAGE(page_to_pgoff(page) != offset, page);
+ VM_BUG_ON_PAGE(!thp_contains(page, index), page);
}
return page;
}
--- a/mm/shmem.c~mm-shmem-return-head-page-from-find_lock_entry
+++ a/mm/shmem.c
@@ -1803,7 +1803,7 @@ static int shmem_getpage_gfp(struct inod
struct mm_struct *charge_mm;
struct page *page;
enum sgp_type sgp_huge = sgp;
- pgoff_t hindex = index;
+ pgoff_t hindex;
int error;
int once = 0;
int alloced = 0;
@@ -1843,10 +1843,8 @@ repeat:
put_page(page);
page = NULL;
}
- if (page || sgp == SGP_READ) {
- *pagep = page;
- return 0;
- }
+ if (page || sgp == SGP_READ)
+ goto out;
/*
* Fast cache lookup did not find it:
@@ -1971,14 +1969,13 @@ clear:
* it now, lest undo on failure cancel our earlier guarantee.
*/
if (sgp != SGP_WRITE && !PageUptodate(page)) {
- struct page *head = compound_head(page);
int i;
- for (i = 0; i < compound_nr(head); i++) {
- clear_highpage(head + i);
- flush_dcache_page(head + i);
+ for (i = 0; i < compound_nr(page); i++) {
+ clear_highpage(page + i);
+ flush_dcache_page(page + i);
}
- SetPageUptodate(head);
+ SetPageUptodate(page);
}
/* Perhaps the file has been truncated since we checked */
@@ -1994,7 +1991,8 @@ clear:
error = -EINVAL;
goto unlock;
}
- *pagep = page + index - hindex;
+out:
+ *pagep = page + index - page->index;
return 0;
/*
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-debug-do-not-dereference-i_ino-blindly.patch
mm-factor-find_get_incore_page-out-of-mincore_page.patch
mm-use-find_get_incore_page-in-memcontrol.patch
mm-optimise-madvise-willneed.patch
proc-optimise-smaps-for-shmem-entries.patch
i915-use-find_lock_page-instead-of-find_lock_entry.patch
mm-convert-find_get_entry-to-return-the-head-page.patch
mm-shmem-return-head-page-from-find_lock_entry.patch
mm-add-find_lock_head.patch
mm-account-pmd-tables-like-pte-tables.patch
mm-move-pagedoublemap-bit.patch
mm-simplify-pagedoublemap-with-pf_second-policy.patch
xarray-add-xa_get_order.patch
xarray-add-xas_split.patch
xarray-add-xas_split-fix-2.patch
mm-filemap-fix-storing-to-a-thp-shadow-entry.patch
mm-filemap-fix-page-cache-removal-for-arbitrary-sized-thps.patch
mm-memory-remove-page-fault-assumption-of-compound-page-size.patch
mm-page_owner-change-split_page_owner-to-take-a-count.patch
mm-huge_memory-fix-page_trans_huge_mapcount-assumption-of-thp-size.patch
mm-huge_memory-fix-can_split_huge_page-assumption-of-thp-size.patch
mm-rmap-fix-assumptions-of-thp-size.patch
mm-truncate-fix-truncation-for-pages-of-arbitrary-size.patch
mm-page-writeback-support-tail-pages-in-wait_for_stable_page.patch
mm-vmscan-allow-arbitrary-sized-pages-to-be-paged-out.patch
mm-readahead-add-define_readahead.patch
mm-readahead-make-page_cache_ra_unbounded-take-a-readahead_control.patch
mm-readahead-make-do_page_cache_ra-take-a-readahead_control.patch
mm-readahead-add-page_cache_sync_ra-and-page_cache_async_ra.patch
harden-autofs-ioctl-table.patch
