[RFC PATCH v4 1/3] mm: Merge folio_has_private()/filemap_release_folio() call pairs
From: David Howells
Date: Wed Nov 23 2022 - 17:51:15 EST
Make filemap_release_folio() check folio_has_private(). Then, in most
cases, where a call to folio_has_private() is immediately followed by a
call to filemap_release_folio(), we can get rid of the test in the pair.
The same is done to page_has_private()/try_to_release_page() call pairs.
There are a couple of sites in mm/vscan.c that this can't so easily be
done. In shrink_folio_list(), there are actually three cases (something
different is done for incompletely invalidated buffers), but
filemap_release_folio() elides two of them.
In shrink_active_list(), we don't have have the folio lock yet, so the
check allows us to avoid locking the page unnecessarily.
A wrapper function to check if a folio needs release is provided for those
places that still need to do it in the mm/ directory. This will acquire
additional parts to the condition in a future patch.
Changes:
========
ver #4)
- Split from fscache fix.
- Moved folio_needs_release() to mm/internal.h and removed open-coded
version from filemap_release_folio().
ver #3)
- Fixed mapping_clear_release_always() to use clear_bit() not set_bit().
- Moved a '&&' to the correct line.
ver #2)
- Rewrote entirely according to Willy's suggestion[1].
Reported-by: Rohith Surabattula <rohiths.msft@xxxxxxxxx>
Suggested-by: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Signed-off-by: David Howells <dhowells@xxxxxxxxxx>
cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
cc: Steve French <sfrench@xxxxxxxxx>
cc: Shyam Prasad N <nspmangalore@xxxxxxxxx>
cc: Rohith Surabattula <rohiths.msft@xxxxxxxxx>
cc: Dave Wysochanski <dwysocha@xxxxxxxxxx>
cc: Dominique Martinet <asmadeus@xxxxxxxxxxxxx>
cc: Ilya Dryomov <idryomov@xxxxxxxxx>
cc: linux-cachefs@xxxxxxxxxx
cc: linux-cifs@xxxxxxxxxxxxxxx
cc: linux-afs@xxxxxxxxxxxxxxxxxxx
cc: v9fs-developer@xxxxxxxxxxxxxxxxxxxxx
cc: ceph-devel@xxxxxxxxxxxxxxx
cc: linux-nfs@xxxxxxxxxxxxxxx
cc: linux-fsdevel@xxxxxxxxxxxxxxx
cc: linux-mm@xxxxxxxxx
Link: https://lore.kernel.org/r/Yk9V/03wgdYi65Lb@xxxxxxxxxxxxxxxxxxxx/ [1]
Link: https://lore.kernel.org/r/164928630577.457102.8519251179327601178.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v1
Link: https://lore.kernel.org/r/166844174069.1124521.10890506360974169994.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v2
Link: https://lore.kernel.org/r/166869495238.3720468.4878151409085146764.stgit@xxxxxxxxxxxxxxxxxxxxxx/ # v3
Link: https://lore.kernel.org/r/1459152.1669208550@xxxxxxxxxxxxxxxxxxxxxx/ # v3 also
---
fs/splice.c | 3 +--
mm/filemap.c | 2 ++
mm/huge_memory.c | 3 +--
mm/internal.h | 8 ++++++++
mm/khugepaged.c | 3 +--
mm/memory-failure.c | 3 +--
mm/migrate.c | 3 +--
mm/truncate.c | 6 ++----
mm/vmscan.c | 7 +++----
9 files changed, 20 insertions(+), 18 deletions(-)
diff --git a/fs/splice.c b/fs/splice.c
index 0878b852b355..563105304ccc 100644
--- a/fs/splice.c
+++ b/fs/splice.c
@@ -65,8 +65,7 @@ static bool page_cache_pipe_buf_try_steal(struct pipe_inode_info *pipe,
*/
folio_wait_writeback(folio);
- if (folio_has_private(folio) &&
- !filemap_release_folio(folio, GFP_KERNEL))
+ if (!filemap_release_folio(folio, GFP_KERNEL))
goto out_unlock;
/*
diff --git a/mm/filemap.c b/mm/filemap.c
index 08341616ae7a..93757247cd11 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3941,6 +3941,8 @@ bool filemap_release_folio(struct folio *folio, gfp_t gfp)
struct address_space * const mapping = folio->mapping;
BUG_ON(!folio_test_locked(folio));
+ if (!folio_needs_release(folio))
+ return true;
if (folio_test_writeback(folio))
return false;
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 811d19b5c4f6..308d36aa3197 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2683,8 +2683,7 @@ int split_huge_page_to_list(struct page *page, struct list_head *list)
gfp = current_gfp_context(mapping_gfp_mask(mapping) &
GFP_RECLAIM_MASK);
- if (folio_test_private(folio) &&
- !filemap_release_folio(folio, gfp)) {
+ if (!filemap_release_folio(folio, gfp)) {
ret = -EBUSY;
goto out;
}
diff --git a/mm/internal.h b/mm/internal.h
index 6b7ef495b56d..1fefb5181ab7 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -163,6 +163,14 @@ static inline void set_page_refcounted(struct page *page)
set_page_count(page, 1);
}
+/*
+ * Return true if a folio needs ->release_folio() calling upon it.
+ */
+static inline bool folio_needs_release(struct folio *folio)
+{
+ return folio_has_private(folio);
+}
+
extern unsigned long highest_memmap_pfn;
/*
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 4734315f7940..7e9e0e3e678e 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1883,8 +1883,7 @@ static int collapse_file(struct mm_struct *mm, unsigned long addr,
goto out_unlock;
}
- if (page_has_private(page) &&
- !try_to_release_page(page, GFP_KERNEL)) {
+ if (!try_to_release_page(page, GFP_KERNEL)) {
result = SCAN_PAGE_HAS_PRIVATE;
putback_lru_page(page);
goto out_unlock;
diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index bead6bccc7f2..82673fc01eed 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -831,8 +831,7 @@ static int truncate_error_page(struct page *p, unsigned long pfn,
if (err != 0) {
pr_info("%#lx: Failed to punch page: %d\n", pfn, err);
- } else if (page_has_private(p) &&
- !try_to_release_page(p, GFP_NOIO)) {
+ } else if (!try_to_release_page(p, GFP_NOIO)) {
pr_info("%#lx: failed to release buffers\n", pfn);
} else {
ret = MF_RECOVERED;
diff --git a/mm/migrate.c b/mm/migrate.c
index dff333593a8a..d721ef340943 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -905,8 +905,7 @@ static int fallback_migrate_folio(struct address_space *mapping,
* Buffers may be managed in a filesystem specific way.
* We must have no buffers or drop them.
*/
- if (folio_test_private(src) &&
- !filemap_release_folio(src, GFP_KERNEL))
+ if (!filemap_release_folio(src, GFP_KERNEL))
return mode == MIGRATE_SYNC ? -EAGAIN : -EBUSY;
return migrate_folio(mapping, dst, src, mode);
diff --git a/mm/truncate.c b/mm/truncate.c
index c0be77e5c008..0d4dd233f518 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -19,7 +19,6 @@
#include <linux/highmem.h>
#include <linux/pagevec.h>
#include <linux/task_io_accounting_ops.h>
-#include <linux/buffer_head.h> /* grr. try_to_release_page */
#include <linux/shmem_fs.h>
#include <linux/rmap.h>
#include "internal.h"
@@ -276,7 +275,7 @@ static long mapping_evict_folio(struct address_space *mapping,
if (folio_ref_count(folio) >
folio_nr_pages(folio) + folio_has_private(folio) + 1)
return 0;
- if (folio_has_private(folio) && !filemap_release_folio(folio, 0))
+ if (!filemap_release_folio(folio, 0))
return 0;
return remove_mapping(mapping, folio);
@@ -581,8 +580,7 @@ static int invalidate_complete_folio2(struct address_space *mapping,
if (folio->mapping != mapping)
return 0;
- if (folio_has_private(folio) &&
- !filemap_release_folio(folio, GFP_KERNEL))
+ if (!filemap_release_folio(folio, GFP_KERNEL))
return 0;
spin_lock(&mapping->host->i_lock);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 04d8b88e5216..b9316f447238 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1978,7 +1978,7 @@ static unsigned int shrink_folio_list(struct list_head *folio_list,
* (refcount == 1) it can be freed. Otherwise, leave
* the folio on the LRU so it is swappable.
*/
- if (folio_has_private(folio)) {
+ if (folio_needs_release(folio)) {
if (!filemap_release_folio(folio, sc->gfp_mask))
goto activate_locked;
if (!mapping && folio_ref_count(folio) == 1) {
@@ -2592,9 +2592,8 @@ static void shrink_active_list(unsigned long nr_to_scan,
}
if (unlikely(buffer_heads_over_limit)) {
- if (folio_test_private(folio) && folio_trylock(folio)) {
- if (folio_test_private(folio))
- filemap_release_folio(folio, 0);
+ if (folio_needs_release(folio) && folio_trylock(folio)) {
+ filemap_release_folio(folio, 0);
folio_unlock(folio);
}
}