* better block swap batching and a different take on swap_ops v3
@ 2026-07-06 9:29 Christoph Hellwig
2026-07-06 9:29 ` [PATCH 1/7] shmem: provide a shmem_write_folio wrapper Christoph Hellwig
0 siblings, 1 reply; 3+ messages in thread
From: Christoph Hellwig @ 2026-07-06 9:29 UTC (permalink / raw)
Cc: baoquan.he, akpm, chrisl, usama.arif, kasong, nphamcs, shikemeng,
youngjun.park, linux-mm
Hi all,
this series makes use of the swap_iocb for block as well so that it
doesn't do inefficient single-bio I/O, and then rebases the swap_ops from
Baoquan on top of the now very different method structure.
When running doing kernels builds, which is a workload that doesn't
really do much THP anonymous memory it still gets 2x clustering for
writeout and 1.2x for reading back swap in. The overall times do
not actually change, though.
Changes since v2:
- rebased to 7.2-rc2
- rename swap_add_page to swap_add_folio
- rename SWAP_OPS_F_NOFS to SWAP_OPS_F_REQUIRE_NOFS and document it
- improve various commit logs
- spelling fixes
Changes since v1:
- drop the memcg accounting for fs backed swap as it can't really
work as-is
- change the related refactoring to not create a bisection hazard or
compile issue with the wrong set of cgroup config options enabled
- remove a now dead function
Diffstat:
Documentation/filesystems/locking.rst | 5
Documentation/filesystems/vfs.rst | 4
drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 2
drivers/gpu/drm/ttm/ttm_backup.c | 2
fs/nfs/file.c | 4
fs/smb/client/file.c | 4
include/linux/shmem_fs.h | 5
include/linux/swap.h | 7
include/linux/vm_event_item.h | 4
mm/madvise.c | 16
mm/page_io.c | 585 ++++++++++++++----------------
mm/shmem.c | 18
mm/swap.h | 67 +--
mm/swap_state.c | 53 +-
mm/swapfile.c | 11
mm/vmscan.c | 30 -
mm/vmstat.c | 6
mm/zswap.c | 4
18 files changed, 431 insertions(+), 396 deletions(-)
^ permalink raw reply [flat|nested] 3+ messages in thread
* [PATCH 1/7] shmem: provide a shmem_write_folio wrapper
2026-07-06 9:29 better block swap batching and a different take on swap_ops v3 Christoph Hellwig
@ 2026-07-06 9:29 ` Christoph Hellwig
0 siblings, 0 replies; 3+ messages in thread
From: Christoph Hellwig @ 2026-07-06 9:29 UTC (permalink / raw)
Cc: baoquan.he, akpm, chrisl, usama.arif, kasong, nphamcs, shikemeng,
youngjun.park, linux-mm
Provide a wrapper for the shmem abuses in drm to prepare for swap I/O
refactoring by keeping swap_iocb handling entirely contained in mm/.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Baoquan He <baoquan.he@linux.dev>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Chris Li <chrisl@kernel.org>
---
drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 2 +-
drivers/gpu/drm/ttm/ttm_backup.c | 2 +-
include/linux/shmem_fs.h | 5 +----
mm/shmem.c | 7 ++++++-
mm/swap.h | 4 ++++
5 files changed, 13 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
index 06543ae60706..ef9440166295 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -325,7 +325,7 @@ void __shmem_writeback(size_t size, struct address_space *mapping)
if (folio_mapped(folio))
folio_redirty_for_writepage(&wbc, folio);
else
- error = shmem_writeout(folio, NULL, NULL);
+ error = shmem_write_folio(folio);
}
}
diff --git a/drivers/gpu/drm/ttm/ttm_backup.c b/drivers/gpu/drm/ttm/ttm_backup.c
index 81df4cb5606b..c5b813a563e7 100644
--- a/drivers/gpu/drm/ttm/ttm_backup.c
+++ b/drivers/gpu/drm/ttm/ttm_backup.c
@@ -117,7 +117,7 @@ ttm_backup_backup_page(struct file *backup, struct page *page,
if (writeback && !folio_mapped(to_folio) &&
folio_clear_dirty_for_io(to_folio)) {
folio_set_reclaim(to_folio);
- ret = shmem_writeout(to_folio, NULL, NULL);
+ ret = shmem_write_folio(to_folio);
if (!folio_test_writeback(to_folio))
folio_clear_reclaim(to_folio);
/*
diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index e729b9b0e38d..5663dff53186 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -12,8 +12,6 @@
#include <linux/userfaultfd_k.h>
#include <linux/bits.h>
-struct swap_iocb;
-
/* inode in-kernel data */
#ifdef CONFIG_TMPFS_QUOTA
@@ -123,8 +121,7 @@ static inline bool shmem_mapping(const struct address_space *mapping)
void shmem_unlock_mapping(struct address_space *mapping);
struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
pgoff_t index, gfp_t gfp_mask);
-int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
- struct list_head *folio_list);
+int shmem_write_folio(struct folio *folio);
void shmem_truncate_range(struct inode *inode, loff_t start, uoff_t end);
int shmem_unuse(unsigned int type);
diff --git a/mm/shmem.c b/mm/shmem.c
index b51f83c970bb..6011a7f729ae 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1736,7 +1736,12 @@ int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
folio_mark_dirty(folio);
return AOP_WRITEPAGE_ACTIVATE; /* Return with folio locked */
}
-EXPORT_SYMBOL_GPL(shmem_writeout);
+
+int shmem_write_folio(struct folio *folio)
+{
+ return shmem_writeout(folio, NULL, NULL);
+}
+EXPORT_SYMBOL_GPL(shmem_write_folio);
#if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
diff --git a/mm/swap.h b/mm/swap.h
index 77d2d14eda42..4f86ef338a60 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -473,4 +473,8 @@ static inline unsigned int folio_swap_flags(struct folio *folio)
}
#endif /* CONFIG_SWAP */
+
+int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
+ struct list_head *folio_list);
+
#endif /* _MM_SWAP_H */
--
2.53.0
^ permalink raw reply related [flat|nested] 3+ messages in thread
* [PATCH 1/7] shmem: provide a shmem_write_folio wrapper
2026-07-06 13:21 better block swap batching and a different take on swap_ops v3 Christoph Hellwig
@ 2026-07-06 13:21 ` Christoph Hellwig
0 siblings, 0 replies; 3+ messages in thread
From: Christoph Hellwig @ 2026-07-06 13:21 UTC (permalink / raw)
Cc: baoquan.he, akpm, chrisl, usama.arif, kasong, nphamcs, shikemeng,
youngjun.park, linux-mm
Provide a wrapper for the shmem abuses in drm to prepare for swap I/O
refactoring by keeping swap_iocb handling entirely contained in mm/.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Baoquan He <baoquan.he@linux.dev>
Reviewed-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Chris Li <chrisl@kernel.org>
---
drivers/gpu/drm/i915/gem/i915_gem_shmem.c | 2 +-
drivers/gpu/drm/ttm/ttm_backup.c | 2 +-
include/linux/shmem_fs.h | 5 +----
mm/shmem.c | 7 ++++++-
mm/swap.h | 4 ++++
5 files changed, 13 insertions(+), 7 deletions(-)
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
index 06543ae60706..ef9440166295 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
@@ -325,7 +325,7 @@ void __shmem_writeback(size_t size, struct address_space *mapping)
if (folio_mapped(folio))
folio_redirty_for_writepage(&wbc, folio);
else
- error = shmem_writeout(folio, NULL, NULL);
+ error = shmem_write_folio(folio);
}
}
diff --git a/drivers/gpu/drm/ttm/ttm_backup.c b/drivers/gpu/drm/ttm/ttm_backup.c
index 81df4cb5606b..c5b813a563e7 100644
--- a/drivers/gpu/drm/ttm/ttm_backup.c
+++ b/drivers/gpu/drm/ttm/ttm_backup.c
@@ -117,7 +117,7 @@ ttm_backup_backup_page(struct file *backup, struct page *page,
if (writeback && !folio_mapped(to_folio) &&
folio_clear_dirty_for_io(to_folio)) {
folio_set_reclaim(to_folio);
- ret = shmem_writeout(to_folio, NULL, NULL);
+ ret = shmem_write_folio(to_folio);
if (!folio_test_writeback(to_folio))
folio_clear_reclaim(to_folio);
/*
diff --git a/include/linux/shmem_fs.h b/include/linux/shmem_fs.h
index e729b9b0e38d..5663dff53186 100644
--- a/include/linux/shmem_fs.h
+++ b/include/linux/shmem_fs.h
@@ -12,8 +12,6 @@
#include <linux/userfaultfd_k.h>
#include <linux/bits.h>
-struct swap_iocb;
-
/* inode in-kernel data */
#ifdef CONFIG_TMPFS_QUOTA
@@ -123,8 +121,7 @@ static inline bool shmem_mapping(const struct address_space *mapping)
void shmem_unlock_mapping(struct address_space *mapping);
struct page *shmem_read_mapping_page_gfp(struct address_space *mapping,
pgoff_t index, gfp_t gfp_mask);
-int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
- struct list_head *folio_list);
+int shmem_write_folio(struct folio *folio);
void shmem_truncate_range(struct inode *inode, loff_t start, uoff_t end);
int shmem_unuse(unsigned int type);
diff --git a/mm/shmem.c b/mm/shmem.c
index b51f83c970bb..6011a7f729ae 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1736,7 +1736,12 @@ int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
folio_mark_dirty(folio);
return AOP_WRITEPAGE_ACTIVATE; /* Return with folio locked */
}
-EXPORT_SYMBOL_GPL(shmem_writeout);
+
+int shmem_write_folio(struct folio *folio)
+{
+ return shmem_writeout(folio, NULL, NULL);
+}
+EXPORT_SYMBOL_GPL(shmem_write_folio);
#if defined(CONFIG_NUMA) && defined(CONFIG_TMPFS)
static void shmem_show_mpol(struct seq_file *seq, struct mempolicy *mpol)
diff --git a/mm/swap.h b/mm/swap.h
index 77d2d14eda42..4f86ef338a60 100644
--- a/mm/swap.h
+++ b/mm/swap.h
@@ -473,4 +473,8 @@ static inline unsigned int folio_swap_flags(struct folio *folio)
}
#endif /* CONFIG_SWAP */
+
+int shmem_writeout(struct folio *folio, struct swap_iocb **plug,
+ struct list_head *folio_list);
+
#endif /* _MM_SWAP_H */
--
2.53.0
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