The patch titled
Subject: mm: use folio_xor_flags_has_waiters() in folio_end_writeback()
has been added to the -mm mm-unstable branch. Its filename is
mm-use-folio_xor_flags_has_waiters-in-folio_end_writeback.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-use-folio_xor_flags_has_waiters-in-folio_end_writeback.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Subject: mm: use folio_xor_flags_has_waiters() in folio_end_writeback()
Date: Wed, 4 Oct 2023 17:53:17 +0100
Match how folio_unlock() works by combining the test for PG_waiters with
the clearing of PG_writeback. This should have a small performance win,
and removes the last user of folio_wake().
Link: https://lkml.kernel.org/r/20231004165317.1061855-18-willy@xxxxxxxxxxxxx
Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Cc: Albert Ou <aou@xxxxxxxxxxxxxxxxx>
Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Cc: Andreas Dilger <adilger.kernel@xxxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Cc: Heiko Carstens <hca@xxxxxxxxxxxxx>
Cc: Ivan Kokshaysky <ink@xxxxxxxxxxxxxxxxxxxx>
Cc: Matt Turner <mattst88@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Palmer Dabbelt <palmer@xxxxxxxxxxx>
Cc: Paul Walmsley <paul.walmsley@xxxxxxxxxx>
Cc: Richard Henderson <richard.henderson@xxxxxxxxxx>
Cc: Sven Schnelle <svens@xxxxxxxxxxxxx>
Cc: "Theodore Ts'o" <tytso@xxxxxxx>
Cc: Thomas Bogendoerfer <tsbogend@xxxxxxxxxxxxxxxx>
Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 15 +++------------
mm/internal.h | 2 +-
mm/page-writeback.c | 9 ++++++---
3 files changed, 10 insertions(+), 16 deletions(-)
--- a/mm/filemap.c~mm-use-folio_xor_flags_has_waiters-in-folio_end_writeback
+++ a/mm/filemap.c
@@ -1175,13 +1175,6 @@ static void folio_wake_bit(struct folio
spin_unlock_irqrestore(&q->lock, flags);
}
-static void folio_wake(struct folio *folio, int bit)
-{
- if (!folio_test_waiters(folio))
- return;
- folio_wake_bit(folio, bit);
-}
-
/*
* A choice of three behaviors for folio_wait_bit_common():
*/
@@ -1618,13 +1611,11 @@ void folio_end_writeback(struct folio *f
* Writeback does not hold a folio reference of its own, relying
* on truncation to wait for the clearing of PG_writeback.
* But here we must make sure that the folio is not freed and
- * reused before the folio_wake().
+ * reused before the folio_wake_bit().
*/
folio_get(folio);
- __folio_end_writeback(folio);
-
- smp_mb__after_atomic();
- folio_wake(folio, PG_writeback);
+ if (__folio_end_writeback(folio))
+ folio_wake_bit(folio, PG_writeback);
acct_reclaim_writeback(folio);
folio_put(folio);
}
--- a/mm/internal.h~mm-use-folio_xor_flags_has_waiters-in-folio_end_writeback
+++ a/mm/internal.h
@@ -105,7 +105,7 @@ static inline void wake_throttle_isolate
vm_fault_t do_swap_page(struct vm_fault *vmf);
void folio_rotate_reclaimable(struct folio *folio);
-void __folio_end_writeback(struct folio *folio);
+bool __folio_end_writeback(struct folio *folio);
void deactivate_file_folio(struct folio *folio);
void folio_activate(struct folio *folio);
--- a/mm/page-writeback.c~mm-use-folio_xor_flags_has_waiters-in-folio_end_writeback
+++ a/mm/page-writeback.c
@@ -2940,10 +2940,11 @@ static void wb_inode_writeback_end(struc
spin_unlock_irqrestore(&wb->work_lock, flags);
}
-void __folio_end_writeback(struct folio *folio)
+bool __folio_end_writeback(struct folio *folio)
{
long nr = folio_nr_pages(folio);
struct address_space *mapping = folio_mapping(folio);
+ bool ret;
folio_memcg_lock(folio);
if (mapping && mapping_use_writeback_tags(mapping)) {
@@ -2952,7 +2953,7 @@ void __folio_end_writeback(struct folio
unsigned long flags;
xa_lock_irqsave(&mapping->i_pages, flags);
- folio_test_clear_writeback(folio);
+ ret = folio_xor_flags_has_waiters(folio, 1 << PG_writeback);
__xa_clear_mark(&mapping->i_pages, folio_index(folio),
PAGECACHE_TAG_WRITEBACK);
if (bdi->capabilities & BDI_CAP_WRITEBACK_ACCT) {
@@ -2970,13 +2971,15 @@ void __folio_end_writeback(struct folio
xa_unlock_irqrestore(&mapping->i_pages, flags);
} else {
- folio_test_clear_writeback(folio);
+ ret = folio_xor_flags_has_waiters(folio, 1 << PG_writeback);
}
lruvec_stat_mod_folio(folio, NR_WRITEBACK, -nr);
zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, -nr);
node_stat_mod_folio(folio, NR_WRITTEN, nr);
folio_memcg_unlock(folio);
+
+ return ret;
}
bool __folio_start_writeback(struct folio *folio, bool keep_write)
_
Patches currently in -mm which might be from willy@xxxxxxxxxxxxx are
mm-make-lock_folio_maybe_drop_mmap-vma-lock-aware.patch
mm-call-wp_page_copy-under-the-vma-lock.patch
mm-handle-shared-faults-under-the-vma-lock.patch
mm-handle-cow-faults-under-the-vma-lock.patch
mm-handle-read-faults-under-the-vma-lock.patch
mm-handle-write-faults-to-ro-pages-under-the-vma-lock.patch
iomap-hold-state_lock-over-call-to-ifs_set_range_uptodate.patch
iomap-protect-read_bytes_pending-with-the-state_lock.patch
mm-add-folio_end_read.patch
ext4-use-folio_end_read.patch
buffer-use-folio_end_read.patch
iomap-use-folio_end_read.patch
bitops-add-xor_unlock_is_negative_byte.patch
alpha-implement-xor_unlock_is_negative_byte.patch
m68k-implement-xor_unlock_is_negative_byte.patch
mips-implement-xor_unlock_is_negative_byte.patch
powerpc-implement-arch_xor_unlock_is_negative_byte-on-32-bit.patch
riscv-implement-xor_unlock_is_negative_byte.patch
s390-implement-arch_xor_unlock_is_negative_byte.patch
mm-delete-checks-for-xor_unlock_is_negative_byte.patch
mm-add-folio_xor_flags_has_waiters.patch
mm-make-__end_folio_writeback-return-void.patch
mm-use-folio_xor_flags_has_waiters-in-folio_end_writeback.patch
