[RFC PATCH v8 3/7] mm/filemap: Add mempolicy support to the filemap layer

Shivank Garg posted 7 patches 3 months, 3 weeks ago
There is a newer version of this series
[RFC PATCH v8 3/7] mm/filemap: Add mempolicy support to the filemap layer
Posted by Shivank Garg 3 months, 3 weeks ago
From: Shivansh Dhiman <shivansh.dhiman@amd.com>

Add NUMA mempolicy support to the filemap allocation path by introducing
new APIs that take a mempolicy argument:
- filemap_grab_folio_mpol()
- filemap_alloc_folio_mpol()
- __filemap_get_folio_mpol()

These APIs allow callers to specify a NUMA policy during page cache
allocations, enabling fine-grained control over memory placement. This is
particularly needed by KVM when using guest-memfd memory backends, where
the guest memory needs to be allocated according to the NUMA policy
specified by VMM.

The existing non-mempolicy APIs remain unchanged and continue to use the
default allocation behavior.

Signed-off-by: Shivansh Dhiman <shivansh.dhiman@amd.com>
Co-developed-by: Shivank Garg <shivankg@amd.com>
Signed-off-by: Shivank Garg <shivankg@amd.com>
---
 include/linux/pagemap.h | 41 +++++++++++++++++++++++++++++++++++++++++
 mm/filemap.c            | 27 +++++++++++++++++++++++----
 2 files changed, 64 insertions(+), 4 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index e63fbfbd5b0f..6558c672740d 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -647,15 +647,24 @@ static inline void *detach_page_private(struct page *page)
 
 #ifdef CONFIG_NUMA
 struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order);
+struct folio *filemap_alloc_folio_mpol_noprof(gfp_t gfp, unsigned int order,
+		struct mempolicy *mpol, pgoff_t ilx);
 #else
 static inline struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order)
 {
 	return folio_alloc_noprof(gfp, order);
 }
+static inline struct folio *filemap_alloc_folio_mpol_noprof(gfp_t gfp,
+		unsigned int order, struct mempolicy *mpol, pgoff_t ilx)
+{
+	return filemap_alloc_folio_noprof(gfp, order);
+}
 #endif
 
 #define filemap_alloc_folio(...)				\
 	alloc_hooks(filemap_alloc_folio_noprof(__VA_ARGS__))
+#define filemap_alloc_folio_mpol(...)				\
+	alloc_hooks(filemap_alloc_folio_mpol_noprof(__VA_ARGS__))
 
 static inline struct page *__page_cache_alloc(gfp_t gfp)
 {
@@ -747,6 +756,8 @@ static inline fgf_t fgf_set_order(size_t size)
 void *filemap_get_entry(struct address_space *mapping, pgoff_t index);
 struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
 		fgf_t fgp_flags, gfp_t gfp);
+struct folio *__filemap_get_folio_mpol(struct address_space *mapping,
+		pgoff_t index, fgf_t fgp_flags, gfp_t gfp, struct mempolicy *mpol, pgoff_t ilx);
 struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
 		fgf_t fgp_flags, gfp_t gfp);
 
@@ -805,6 +816,36 @@ static inline struct folio *filemap_grab_folio(struct address_space *mapping,
 			mapping_gfp_mask(mapping));
 }
 
+/**
+ * filemap_grab_folio_mpol - grab a folio from the page cache.
+ * @mapping: The address space to search.
+ * @index: The page index.
+ * @mpol: The mempolicy to apply when allocating a new folio.
+ * @ilx: The interleave index, for use only with MPOL_INTERLEAVE or
+ *       MPOL_WEIGHTED_INTERLEAVE.
+ *
+ * Same as filemap_grab_folio(), except that it allocates the folio using
+ * given memory policy.
+ *
+ * Return: A found or created folio. ERR_PTR(-ENOMEM) if no folio is found
+ * and failed to create a folio.
+ */
+#ifdef CONFIG_NUMA
+static inline struct folio *filemap_grab_folio_mpol(struct address_space *mapping,
+					pgoff_t index, struct mempolicy *mpol, pgoff_t ilx)
+{
+	return __filemap_get_folio_mpol(mapping, index,
+			FGP_LOCK | FGP_ACCESSED | FGP_CREAT,
+			mapping_gfp_mask(mapping), mpol, ilx);
+}
+#else
+static inline struct folio *filemap_grab_folio_mpol(struct address_space *mapping,
+					pgoff_t index, struct mempolicy *mpol, pgoff_t ilx)
+{
+	return filemap_grab_folio(mapping, index);
+}
+#endif /* CONFIG_NUMA */
+
 /**
  * find_get_page - find and get a page reference
  * @mapping: the address_space to search
diff --git a/mm/filemap.c b/mm/filemap.c
index bada249b9fb7..c7e913b91636 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1007,6 +1007,15 @@ struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order)
 	return folio_alloc_noprof(gfp, order);
 }
 EXPORT_SYMBOL(filemap_alloc_folio_noprof);
+
+struct folio *filemap_alloc_folio_mpol_noprof(gfp_t gfp, unsigned int order,
+		struct mempolicy *mpol, pgoff_t ilx)
+{
+	if (mpol)
+		return folio_alloc_mpol_noprof(gfp, order, mpol,
+					       ilx, numa_node_id());
+	return filemap_alloc_folio_noprof(gfp, order);
+}
 #endif
 
 /*
@@ -1891,11 +1900,14 @@ void *filemap_get_entry(struct address_space *mapping, pgoff_t index)
 }
 
 /**
- * __filemap_get_folio - Find and get a reference to a folio.
+ * __filemap_get_folio_mpol - Find and get a reference to a folio.
  * @mapping: The address_space to search.
  * @index: The page index.
  * @fgp_flags: %FGP flags modify how the folio is returned.
  * @gfp: Memory allocation flags to use if %FGP_CREAT is specified.
+ * @mpol: The mempolicy to apply when allocating a new folio.
+ * @ilx: The interleave index, for use only with MPOL_INTERLEAVE or
+ *       MPOL_WEIGHTED_INTERLEAVE.
  *
  * Looks up the page cache entry at @mapping & @index.
  *
@@ -1906,8 +1918,8 @@ void *filemap_get_entry(struct address_space *mapping, pgoff_t index)
  *
  * Return: The found folio or an ERR_PTR() otherwise.
  */
-struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
-		fgf_t fgp_flags, gfp_t gfp)
+struct folio *__filemap_get_folio_mpol(struct address_space *mapping, pgoff_t index,
+		fgf_t fgp_flags, gfp_t gfp, struct mempolicy *mpol, pgoff_t ilx)
 {
 	struct folio *folio;
 
@@ -1977,7 +1989,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
 			err = -ENOMEM;
 			if (order > min_order)
 				alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN;
-			folio = filemap_alloc_folio(alloc_gfp, order);
+			folio = filemap_alloc_folio_mpol(alloc_gfp, order, mpol, ilx);
 			if (!folio)
 				continue;
 
@@ -2024,6 +2036,13 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
 		folio_clear_dropbehind(folio);
 	return folio;
 }
+EXPORT_SYMBOL_GPL(__filemap_get_folio_mpol);
+
+struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
+		fgf_t fgp_flags, gfp_t gfp)
+{
+	return __filemap_get_folio_mpol(mapping, index, fgp_flags, gfp, NULL, 0);
+}
 EXPORT_SYMBOL(__filemap_get_folio);
 
 static inline struct folio *find_get_entry(struct xa_state *xas, pgoff_t max,
-- 
2.43.0
Re: [RFC PATCH v8 3/7] mm/filemap: Add mempolicy support to the filemap layer
Posted by Matthew Wilcox 3 months, 3 weeks ago
On Wed, Jun 18, 2025 at 11:29:31AM +0000, Shivank Garg wrote:
> From: Shivansh Dhiman <shivansh.dhiman@amd.com>
> 
> Add NUMA mempolicy support to the filemap allocation path by introducing
> new APIs that take a mempolicy argument:
> - filemap_grab_folio_mpol()
> - filemap_alloc_folio_mpol()
> - __filemap_get_folio_mpol()

You don't use these APIs in this series, so I can't evaludate whether
any of my suggestiosn for improving this patch would actually work.
NACK.  Introduce the APIs *with a user*.  Come on, this isn't a new
requirement.
Re: [RFC PATCH v8 3/7] mm/filemap: Add mempolicy support to the filemap layer
Posted by Shivank Garg 3 months, 3 weeks ago

On 6/19/2025 9:33 PM, Matthew Wilcox wrote:
> On Wed, Jun 18, 2025 at 11:29:31AM +0000, Shivank Garg wrote:
>> From: Shivansh Dhiman <shivansh.dhiman@amd.com>
>>
>> Add NUMA mempolicy support to the filemap allocation path by introducing
>> new APIs that take a mempolicy argument:
>> - filemap_grab_folio_mpol()
>> - filemap_alloc_folio_mpol()
>> - __filemap_get_folio_mpol()
> 
> You don't use these APIs in this series, so I can't evaludate whether
> any of my suggestiosn for improving this patch would actually work.
> NACK.  Introduce the APIs *with a user*.  Come on, this isn't a new
> requirement.

Hi willy,

Thank you for the feedback.

filemap_grab_folio_mpol() is used in [Patch 6/7] in kvm_gmem_prepare_folio().

filemap_alloc_folio_mpol() and __filemap_get_folio_mpol()) are internally used
to support the filemap_grab_folio_mpol().

Thanks,
Shivank
Re: [RFC PATCH v8 3/7] mm/filemap: Add mempolicy support to the filemap layer
Posted by Matthew Wilcox 3 months, 2 weeks ago
On Fri, Jun 20, 2025 at 11:29:20AM +0530, Shivank Garg wrote:
> filemap_grab_folio_mpol() is used in [Patch 6/7] in kvm_gmem_prepare_folio().
> 
> filemap_alloc_folio_mpol() and __filemap_get_folio_mpol()) are internally used
> to support the filemap_grab_folio_mpol().

That's not better.  We don't add unused functions, and unless there's
something coming that's going to use them, the entire structure of this
is wrong.

filemap_grab_folio() is a convenience function that avoids us having to
specify the other two arguments to __filemap_get_folio().  Since there's
no indication at this point that there are going to be more callers of
it, filemap_grab_folio_mpol() should not even exist.

I'll send a pair of patches which should be sufficient for your needs.
Re: [RFC PATCH v8 3/7] mm/filemap: Add mempolicy support to the filemap layer
Posted by Shivank Garg 3 months, 2 weeks ago

On 6/20/2025 8:04 PM, Matthew Wilcox wrote:
> On Fri, Jun 20, 2025 at 11:29:20AM +0530, Shivank Garg wrote:
>> filemap_grab_folio_mpol() is used in [Patch 6/7] in kvm_gmem_prepare_folio().
>>
>> filemap_alloc_folio_mpol() and __filemap_get_folio_mpol()) are internally used
>> to support the filemap_grab_folio_mpol().
> 
> That's not better.  We don't add unused functions, and unless there's
> something coming that's going to use them, the entire structure of this
> is wrong.
> 
> filemap_grab_folio() is a convenience function that avoids us having to
> specify the other two arguments to __filemap_get_folio().  Since there's
> no indication at this point that there are going to be more callers of
> it, filemap_grab_folio_mpol() should not even exist.
> 
> I'll send a pair of patches which should be sufficient for your needs.

Thank you willy :)
I'll them add to my series.

Thanks,
Shivank
Re: [RFC PATCH v8 3/7] mm/filemap: Add mempolicy support to the filemap layer
Posted by Matthew Wilcox 3 months, 2 weeks ago
On Fri, Jun 20, 2025 at 08:22:49PM +0530, Shivank Garg wrote:
> 
> 
> On 6/20/2025 8:04 PM, Matthew Wilcox wrote:
> > On Fri, Jun 20, 2025 at 11:29:20AM +0530, Shivank Garg wrote:
> >> filemap_grab_folio_mpol() is used in [Patch 6/7] in kvm_gmem_prepare_folio().
> >>
> >> filemap_alloc_folio_mpol() and __filemap_get_folio_mpol()) are internally used
> >> to support the filemap_grab_folio_mpol().
> > 
> > That's not better.  We don't add unused functions, and unless there's
> > something coming that's going to use them, the entire structure of this
> > is wrong.
> > 
> > filemap_grab_folio() is a convenience function that avoids us having to
> > specify the other two arguments to __filemap_get_folio().  Since there's
> > no indication at this point that there are going to be more callers of
> > it, filemap_grab_folio_mpol() should not even exist.
> > 
> > I'll send a pair of patches which should be sufficient for your needs.
> 
> Thank you willy :)
> I'll them add to my series.

Thanks.  You probably want to touch up the commit messages, I didn't
spend very long on them.
Re: [RFC PATCH v8 3/7] mm/filemap: Add mempolicy support to the filemap layer
Posted by Vlastimil Babka 3 months, 2 weeks ago
On 6/20/25 07:59, Shivank Garg wrote:
> 
> 
> On 6/19/2025 9:33 PM, Matthew Wilcox wrote:
>> On Wed, Jun 18, 2025 at 11:29:31AM +0000, Shivank Garg wrote:
>>> From: Shivansh Dhiman <shivansh.dhiman@amd.com>
>>>
>>> Add NUMA mempolicy support to the filemap allocation path by introducing
>>> new APIs that take a mempolicy argument:
>>> - filemap_grab_folio_mpol()
>>> - filemap_alloc_folio_mpol()
>>> - __filemap_get_folio_mpol()
>> 
>> You don't use these APIs in this series, so I can't evaludate whether
>> any of my suggestiosn for improving this patch would actually work.
>> NACK.  Introduce the APIs *with a user*.  Come on, this isn't a new
>> requirement.
> 
> Hi willy,
> 
> Thank you for the feedback.
> 
> filemap_grab_folio_mpol() is used in [Patch 6/7] in kvm_gmem_prepare_folio().
> 
> filemap_alloc_folio_mpol() and __filemap_get_folio_mpol()) are internally used
> to support the filemap_grab_folio_mpol().

Maybe they can be static then and don't need to be declared in the header.

> Thanks,
> Shivank
Re: [RFC PATCH v8 3/7] mm/filemap: Add mempolicy support to the filemap layer
Posted by Vlastimil Babka 3 months, 3 weeks ago
On 6/18/25 13:29, Shivank Garg wrote:
> From: Shivansh Dhiman <shivansh.dhiman@amd.com>
> 
> Add NUMA mempolicy support to the filemap allocation path by introducing
> new APIs that take a mempolicy argument:
> - filemap_grab_folio_mpol()
> - filemap_alloc_folio_mpol()
> - __filemap_get_folio_mpol()
> 
> These APIs allow callers to specify a NUMA policy during page cache
> allocations, enabling fine-grained control over memory placement. This is
> particularly needed by KVM when using guest-memfd memory backends, where
> the guest memory needs to be allocated according to the NUMA policy
> specified by VMM.
> 
> The existing non-mempolicy APIs remain unchanged and continue to use the
> default allocation behavior.
> 
> Signed-off-by: Shivansh Dhiman <shivansh.dhiman@amd.com>
> Co-developed-by: Shivank Garg <shivankg@amd.com>
> Signed-off-by: Shivank Garg <shivankg@amd.com>

I think __filemap_get_folio() could become a static inline wrapper for
__filemap_get_folio_mpol in pagemap.h.
Otherwise,

Acked-by: Vlastimil Babka <vbabka@suse.cz>
[PATCH 1/2] filemap: Add a mempolicy argument to filemap_alloc_folio()
Posted by Matthew Wilcox (Oracle) 3 months, 2 weeks ago
guest_memfd needs to support memory policies so add an argument
to filemap_alloc_folio().  All existing users pass NULL, the first
user will show up later in this series.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 fs/bcachefs/fs-io-buffered.c |  2 +-
 fs/btrfs/compression.c       |  3 ++-
 fs/btrfs/verity.c            |  2 +-
 fs/erofs/zdata.c             |  2 +-
 fs/f2fs/compress.c           |  2 +-
 include/linux/pagemap.h      |  6 +++---
 mm/filemap.c                 | 13 +++++++++----
 mm/readahead.c               |  2 +-
 8 files changed, 19 insertions(+), 13 deletions(-)

diff --git a/fs/bcachefs/fs-io-buffered.c b/fs/bcachefs/fs-io-buffered.c
index 66bacdd49f78..392344232b16 100644
--- a/fs/bcachefs/fs-io-buffered.c
+++ b/fs/bcachefs/fs-io-buffered.c
@@ -124,7 +124,7 @@ static int readpage_bio_extend(struct btree_trans *trans,
 			if (folio && !xa_is_value(folio))
 				break;
 
-			folio = filemap_alloc_folio(readahead_gfp_mask(iter->mapping), order);
+			folio = filemap_alloc_folio(readahead_gfp_mask(iter->mapping), order, NULL);
 			if (!folio)
 				break;
 
diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
index 48d07939fee4..8430ccf70887 100644
--- a/fs/btrfs/compression.c
+++ b/fs/btrfs/compression.c
@@ -475,7 +475,8 @@ static noinline int add_ra_bio_pages(struct inode *inode,
 		}
 
 		folio = filemap_alloc_folio(mapping_gfp_constraint(mapping,
-								   ~__GFP_FS), 0);
+								   ~__GFP_FS),
+				0, NULL);
 		if (!folio)
 			break;
 
diff --git a/fs/btrfs/verity.c b/fs/btrfs/verity.c
index b7a96a005487..c43a789ba6d2 100644
--- a/fs/btrfs/verity.c
+++ b/fs/btrfs/verity.c
@@ -742,7 +742,7 @@ static struct page *btrfs_read_merkle_tree_page(struct inode *inode,
 	}
 
 	folio = filemap_alloc_folio(mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS),
-				    0);
+				    0, NULL);
 	if (!folio)
 		return ERR_PTR(-ENOMEM);
 
diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
index fe8071844724..00e9160a0d24 100644
--- a/fs/erofs/zdata.c
+++ b/fs/erofs/zdata.c
@@ -562,7 +562,7 @@ static void z_erofs_bind_cache(struct z_erofs_frontend *fe)
 			 * Allocate a managed folio for cached I/O, or it may be
 			 * then filled with a file-backed folio for in-place I/O
 			 */
-			newfolio = filemap_alloc_folio(gfp, 0);
+			newfolio = filemap_alloc_folio(gfp, 0, NULL);
 			if (!newfolio)
 				continue;
 			newfolio->private = Z_EROFS_PREALLOCATED_FOLIO;
diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
index b3c1df93a163..7ef937dd7624 100644
--- a/fs/f2fs/compress.c
+++ b/fs/f2fs/compress.c
@@ -1942,7 +1942,7 @@ void f2fs_cache_compressed_page(struct f2fs_sb_info *sbi, struct page *page,
 		return;
 	}
 
-	cfolio = filemap_alloc_folio(__GFP_NOWARN | __GFP_IO, 0);
+	cfolio = filemap_alloc_folio(__GFP_NOWARN | __GFP_IO, 0, NULL);
 	if (!cfolio)
 		return;
 
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index e63fbfbd5b0f..c176aeeb38db 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -646,9 +646,9 @@ static inline void *detach_page_private(struct page *page)
 }
 
 #ifdef CONFIG_NUMA
-struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order);
+struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order, struct mempolicy *policy);
 #else
-static inline struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order)
+static inline struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order, struct mempolicy *policy)
 {
 	return folio_alloc_noprof(gfp, order);
 }
@@ -659,7 +659,7 @@ static inline struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int o
 
 static inline struct page *__page_cache_alloc(gfp_t gfp)
 {
-	return &filemap_alloc_folio(gfp, 0)->page;
+	return &filemap_alloc_folio(gfp, 0, NULL)->page;
 }
 
 static inline gfp_t readahead_gfp_mask(struct address_space *x)
diff --git a/mm/filemap.c b/mm/filemap.c
index bada249b9fb7..a26df313207d 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -989,11 +989,16 @@ int filemap_add_folio(struct address_space *mapping, struct folio *folio,
 EXPORT_SYMBOL_GPL(filemap_add_folio);
 
 #ifdef CONFIG_NUMA
-struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order)
+struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order,
+		struct mempolicy *policy)
 {
 	int n;
 	struct folio *folio;
 
+	if (policy)
+		return folio_alloc_mpol_noprof(gfp, order, policy,
+				NO_INTERLEAVE_INDEX, numa_node_id());
+
 	if (cpuset_do_page_mem_spread()) {
 		unsigned int cpuset_mems_cookie;
 		do {
@@ -1977,7 +1982,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
 			err = -ENOMEM;
 			if (order > min_order)
 				alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN;
-			folio = filemap_alloc_folio(alloc_gfp, order);
+			folio = filemap_alloc_folio(alloc_gfp, order, NULL);
 			if (!folio)
 				continue;
 
@@ -2516,7 +2521,7 @@ static int filemap_create_folio(struct kiocb *iocb, struct folio_batch *fbatch)
 	if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))
 		return -EAGAIN;
 
-	folio = filemap_alloc_folio(mapping_gfp_mask(mapping), min_order);
+	folio = filemap_alloc_folio(mapping_gfp_mask(mapping), min_order, NULL);
 	if (!folio)
 		return -ENOMEM;
 	if (iocb->ki_flags & IOCB_DONTCACHE)
@@ -3854,7 +3859,7 @@ static struct folio *do_read_cache_folio(struct address_space *mapping,
 	folio = filemap_get_folio(mapping, index);
 	if (IS_ERR(folio)) {
 		folio = filemap_alloc_folio(gfp,
-					    mapping_min_folio_order(mapping));
+				mapping_min_folio_order(mapping), NULL);
 		if (!folio)
 			return ERR_PTR(-ENOMEM);
 		index = mapping_align_index(mapping, index);
diff --git a/mm/readahead.c b/mm/readahead.c
index 20d36d6b055e..0b2aec0231e6 100644
--- a/mm/readahead.c
+++ b/mm/readahead.c
@@ -183,7 +183,7 @@ static struct folio *ractl_alloc_folio(struct readahead_control *ractl,
 {
 	struct folio *folio;
 
-	folio = filemap_alloc_folio(gfp_mask, order);
+	folio = filemap_alloc_folio(gfp_mask, order, NULL);
 	if (folio && ractl->dropbehind)
 		__folio_set_dropbehind(folio);
 
-- 
2.47.2
Re: [PATCH 1/2] filemap: Add a mempolicy argument to filemap_alloc_folio()
Posted by Vlastimil Babka 3 months, 2 weeks ago
On 6/20/25 16:34, Matthew Wilcox (Oracle) wrote:
> guest_memfd needs to support memory policies so add an argument
> to filemap_alloc_folio().  All existing users pass NULL, the first
> user will show up later in this series.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Re: [PATCH 1/2] filemap: Add a mempolicy argument to filemap_alloc_folio()
Posted by Gupta, Pankaj 3 months, 2 weeks ago
> guest_memfd needs to support memory policies so add an argument
> to filemap_alloc_folio().  All existing users pass NULL, the first
> user will show up later in this series.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>

> ---
>   fs/bcachefs/fs-io-buffered.c |  2 +-
>   fs/btrfs/compression.c       |  3 ++-
>   fs/btrfs/verity.c            |  2 +-
>   fs/erofs/zdata.c             |  2 +-
>   fs/f2fs/compress.c           |  2 +-
>   include/linux/pagemap.h      |  6 +++---
>   mm/filemap.c                 | 13 +++++++++----
>   mm/readahead.c               |  2 +-
>   8 files changed, 19 insertions(+), 13 deletions(-)
> 
> diff --git a/fs/bcachefs/fs-io-buffered.c b/fs/bcachefs/fs-io-buffered.c
> index 66bacdd49f78..392344232b16 100644
> --- a/fs/bcachefs/fs-io-buffered.c
> +++ b/fs/bcachefs/fs-io-buffered.c
> @@ -124,7 +124,7 @@ static int readpage_bio_extend(struct btree_trans *trans,
>   			if (folio && !xa_is_value(folio))
>   				break;
>   
> -			folio = filemap_alloc_folio(readahead_gfp_mask(iter->mapping), order);
> +			folio = filemap_alloc_folio(readahead_gfp_mask(iter->mapping), order, NULL);
>   			if (!folio)
>   				break;
>   
> diff --git a/fs/btrfs/compression.c b/fs/btrfs/compression.c
> index 48d07939fee4..8430ccf70887 100644
> --- a/fs/btrfs/compression.c
> +++ b/fs/btrfs/compression.c
> @@ -475,7 +475,8 @@ static noinline int add_ra_bio_pages(struct inode *inode,
>   		}
>   
>   		folio = filemap_alloc_folio(mapping_gfp_constraint(mapping,
> -								   ~__GFP_FS), 0);
> +								   ~__GFP_FS),
> +				0, NULL);
>   		if (!folio)
>   			break;
>   
> diff --git a/fs/btrfs/verity.c b/fs/btrfs/verity.c
> index b7a96a005487..c43a789ba6d2 100644
> --- a/fs/btrfs/verity.c
> +++ b/fs/btrfs/verity.c
> @@ -742,7 +742,7 @@ static struct page *btrfs_read_merkle_tree_page(struct inode *inode,
>   	}
>   
>   	folio = filemap_alloc_folio(mapping_gfp_constraint(inode->i_mapping, ~__GFP_FS),
> -				    0);
> +				    0, NULL);
>   	if (!folio)
>   		return ERR_PTR(-ENOMEM);
>   
> diff --git a/fs/erofs/zdata.c b/fs/erofs/zdata.c
> index fe8071844724..00e9160a0d24 100644
> --- a/fs/erofs/zdata.c
> +++ b/fs/erofs/zdata.c
> @@ -562,7 +562,7 @@ static void z_erofs_bind_cache(struct z_erofs_frontend *fe)
>   			 * Allocate a managed folio for cached I/O, or it may be
>   			 * then filled with a file-backed folio for in-place I/O
>   			 */
> -			newfolio = filemap_alloc_folio(gfp, 0);
> +			newfolio = filemap_alloc_folio(gfp, 0, NULL);
>   			if (!newfolio)
>   				continue;
>   			newfolio->private = Z_EROFS_PREALLOCATED_FOLIO;
> diff --git a/fs/f2fs/compress.c b/fs/f2fs/compress.c
> index b3c1df93a163..7ef937dd7624 100644
> --- a/fs/f2fs/compress.c
> +++ b/fs/f2fs/compress.c
> @@ -1942,7 +1942,7 @@ void f2fs_cache_compressed_page(struct f2fs_sb_info *sbi, struct page *page,
>   		return;
>   	}
>   
> -	cfolio = filemap_alloc_folio(__GFP_NOWARN | __GFP_IO, 0);
> +	cfolio = filemap_alloc_folio(__GFP_NOWARN | __GFP_IO, 0, NULL);
>   	if (!cfolio)
>   		return;
>   
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index e63fbfbd5b0f..c176aeeb38db 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -646,9 +646,9 @@ static inline void *detach_page_private(struct page *page)
>   }
>   
>   #ifdef CONFIG_NUMA
> -struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order);
> +struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order, struct mempolicy *policy);
>   #else
> -static inline struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order)
> +static inline struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order, struct mempolicy *policy)
>   {
>   	return folio_alloc_noprof(gfp, order);
>   }
> @@ -659,7 +659,7 @@ static inline struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int o
>   
>   static inline struct page *__page_cache_alloc(gfp_t gfp)
>   {
> -	return &filemap_alloc_folio(gfp, 0)->page;
> +	return &filemap_alloc_folio(gfp, 0, NULL)->page;
>   }
>   
>   static inline gfp_t readahead_gfp_mask(struct address_space *x)
> diff --git a/mm/filemap.c b/mm/filemap.c
> index bada249b9fb7..a26df313207d 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -989,11 +989,16 @@ int filemap_add_folio(struct address_space *mapping, struct folio *folio,
>   EXPORT_SYMBOL_GPL(filemap_add_folio);
>   
>   #ifdef CONFIG_NUMA
> -struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order)
> +struct folio *filemap_alloc_folio_noprof(gfp_t gfp, unsigned int order,
> +		struct mempolicy *policy)
>   {
>   	int n;
>   	struct folio *folio;
>   
> +	if (policy)
> +		return folio_alloc_mpol_noprof(gfp, order, policy,
> +				NO_INTERLEAVE_INDEX, numa_node_id());
> +
>   	if (cpuset_do_page_mem_spread()) {
>   		unsigned int cpuset_mems_cookie;
>   		do {
> @@ -1977,7 +1982,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
>   			err = -ENOMEM;
>   			if (order > min_order)
>   				alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN;
> -			folio = filemap_alloc_folio(alloc_gfp, order);
> +			folio = filemap_alloc_folio(alloc_gfp, order, NULL);
>   			if (!folio)
>   				continue;
>   
> @@ -2516,7 +2521,7 @@ static int filemap_create_folio(struct kiocb *iocb, struct folio_batch *fbatch)
>   	if (iocb->ki_flags & (IOCB_NOWAIT | IOCB_WAITQ))
>   		return -EAGAIN;
>   
> -	folio = filemap_alloc_folio(mapping_gfp_mask(mapping), min_order);
> +	folio = filemap_alloc_folio(mapping_gfp_mask(mapping), min_order, NULL);
>   	if (!folio)
>   		return -ENOMEM;
>   	if (iocb->ki_flags & IOCB_DONTCACHE)
> @@ -3854,7 +3859,7 @@ static struct folio *do_read_cache_folio(struct address_space *mapping,
>   	folio = filemap_get_folio(mapping, index);
>   	if (IS_ERR(folio)) {
>   		folio = filemap_alloc_folio(gfp,
> -					    mapping_min_folio_order(mapping));
> +				mapping_min_folio_order(mapping), NULL);
>   		if (!folio)
>   			return ERR_PTR(-ENOMEM);
>   		index = mapping_align_index(mapping, index);
> diff --git a/mm/readahead.c b/mm/readahead.c
> index 20d36d6b055e..0b2aec0231e6 100644
> --- a/mm/readahead.c
> +++ b/mm/readahead.c
> @@ -183,7 +183,7 @@ static struct folio *ractl_alloc_folio(struct readahead_control *ractl,
>   {
>   	struct folio *folio;
>   
> -	folio = filemap_alloc_folio(gfp_mask, order);
> +	folio = filemap_alloc_folio(gfp_mask, order, NULL);
>   	if (folio && ractl->dropbehind)
>   		__folio_set_dropbehind(folio);
>
[PATCH 2/2] filemap: Add __filemap_get_folio_mpol()
Posted by Matthew Wilcox (Oracle) 3 months, 2 weeks ago
This allows guest_memfd to pass in a memory policy.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 include/linux/pagemap.h | 10 ++++++++--
 mm/filemap.c            | 10 ++++++----
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index c176aeeb38db..1cfbf7b8f573 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -745,11 +745,17 @@ static inline fgf_t fgf_set_order(size_t size)
 }
 
 void *filemap_get_entry(struct address_space *mapping, pgoff_t index);
-struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
-		fgf_t fgp_flags, gfp_t gfp);
+struct folio *__filemap_get_folio_mpol(struct address_space *mapping,
+		pgoff_t index, fgf_t fgf_flags, gfp_t gfp, struct mempolicy *);
 struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
 		fgf_t fgp_flags, gfp_t gfp);
 
+static inline struct folio *__filemap_get_folio(struct address_space *mapping,
+		pgoff_t index, fgf_t fgf_flags, gfp_t gfp)
+{
+	return __filemap_get_folio_mpol(mapping, index, fgf_flags, gfp, NULL);
+}
+
 /**
  * filemap_get_folio - Find and get a folio.
  * @mapping: The address_space to search.
diff --git a/mm/filemap.c b/mm/filemap.c
index a26df313207d..597d146cbb3a 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1896,11 +1896,12 @@ void *filemap_get_entry(struct address_space *mapping, pgoff_t index)
 }
 
 /**
- * __filemap_get_folio - Find and get a reference to a folio.
+ * __filemap_get_folio_mpol - Find and get a reference to a folio.
  * @mapping: The address_space to search.
  * @index: The page index.
  * @fgp_flags: %FGP flags modify how the folio is returned.
  * @gfp: Memory allocation flags to use if %FGP_CREAT is specified.
+ * @policy: NUMA memory allocation policy to follow.
  *
  * Looks up the page cache entry at @mapping & @index.
  *
@@ -1911,8 +1912,9 @@ void *filemap_get_entry(struct address_space *mapping, pgoff_t index)
  *
  * Return: The found folio or an ERR_PTR() otherwise.
  */
-struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
-		fgf_t fgp_flags, gfp_t gfp)
+struct folio *__filemap_get_folio_mpol(struct address_space *mapping,
+		pgoff_t index, fgf_t fgp_flags, gfp_t gfp,
+		struct mempolicy *policy)
 {
 	struct folio *folio;
 
@@ -1982,7 +1984,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
 			err = -ENOMEM;
 			if (order > min_order)
 				alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN;
-			folio = filemap_alloc_folio(alloc_gfp, order, NULL);
+			folio = filemap_alloc_folio(alloc_gfp, order, policy);
 			if (!folio)
 				continue;
 
-- 
2.47.2
Re: [PATCH 2/2] filemap: Add __filemap_get_folio_mpol()
Posted by Vlastimil Babka 3 months, 2 weeks ago
On 6/20/25 16:34, Matthew Wilcox (Oracle) wrote:
> This allows guest_memfd to pass in a memory policy.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Re: [PATCH 2/2] filemap: Add __filemap_get_folio_mpol()
Posted by Gupta, Pankaj 3 months, 2 weeks ago
> This allows guest_memfd to pass in a memory policy.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>

Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>

> ---
>   include/linux/pagemap.h | 10 ++++++++--
>   mm/filemap.c            | 10 ++++++----
>   2 files changed, 14 insertions(+), 6 deletions(-)
> 
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index c176aeeb38db..1cfbf7b8f573 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -745,11 +745,17 @@ static inline fgf_t fgf_set_order(size_t size)
>   }
>   
>   void *filemap_get_entry(struct address_space *mapping, pgoff_t index);
> -struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
> -		fgf_t fgp_flags, gfp_t gfp);
> +struct folio *__filemap_get_folio_mpol(struct address_space *mapping,
> +		pgoff_t index, fgf_t fgf_flags, gfp_t gfp, struct mempolicy *);
>   struct page *pagecache_get_page(struct address_space *mapping, pgoff_t index,
>   		fgf_t fgp_flags, gfp_t gfp);
>   
> +static inline struct folio *__filemap_get_folio(struct address_space *mapping,
> +		pgoff_t index, fgf_t fgf_flags, gfp_t gfp)
> +{
> +	return __filemap_get_folio_mpol(mapping, index, fgf_flags, gfp, NULL);
> +}
> +
>   /**
>    * filemap_get_folio - Find and get a folio.
>    * @mapping: The address_space to search.
> diff --git a/mm/filemap.c b/mm/filemap.c
> index a26df313207d..597d146cbb3a 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -1896,11 +1896,12 @@ void *filemap_get_entry(struct address_space *mapping, pgoff_t index)
>   }
>   
>   /**
> - * __filemap_get_folio - Find and get a reference to a folio.
> + * __filemap_get_folio_mpol - Find and get a reference to a folio.
>    * @mapping: The address_space to search.
>    * @index: The page index.
>    * @fgp_flags: %FGP flags modify how the folio is returned.
>    * @gfp: Memory allocation flags to use if %FGP_CREAT is specified.
> + * @policy: NUMA memory allocation policy to follow.
>    *
>    * Looks up the page cache entry at @mapping & @index.
>    *
> @@ -1911,8 +1912,9 @@ void *filemap_get_entry(struct address_space *mapping, pgoff_t index)
>    *
>    * Return: The found folio or an ERR_PTR() otherwise.
>    */
> -struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
> -		fgf_t fgp_flags, gfp_t gfp)
> +struct folio *__filemap_get_folio_mpol(struct address_space *mapping,
> +		pgoff_t index, fgf_t fgp_flags, gfp_t gfp,
> +		struct mempolicy *policy)
>   {
>   	struct folio *folio;
>   
> @@ -1982,7 +1984,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
>   			err = -ENOMEM;
>   			if (order > min_order)
>   				alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN;
> -			folio = filemap_alloc_folio(alloc_gfp, order, NULL);
> +			folio = filemap_alloc_folio(alloc_gfp, order, policy);
>   			if (!folio)
>   				continue;
>
Re: [PATCH 2/2] filemap: Add __filemap_get_folio_mpol()
Posted by Matthew Wilcox 3 months, 2 weeks ago
On Fri, Jun 20, 2025 at 03:34:47PM +0100, Matthew Wilcox (Oracle) wrote:
> +struct folio *__filemap_get_folio_mpol(struct address_space *mapping,
> +		pgoff_t index, fgf_t fgp_flags, gfp_t gfp,
> +		struct mempolicy *policy)
>  {
>  	struct folio *folio;
>  
> @@ -1982,7 +1984,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
>  			err = -ENOMEM;
>  			if (order > min_order)
>  				alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN;
> -			folio = filemap_alloc_folio(alloc_gfp, order, NULL);
> +			folio = filemap_alloc_folio(alloc_gfp, order, policy);
>  			if (!folio)
>  				continue;

This is missing the EXPORT_SYMBOL_GPL() change.  Sorry about that.
I'm sure you can fix it up ;-)  I only tested "make O=.build-all/ -j16
mm/ fs/" (on an allmodconfig) which doesn't get as far as making sure
that modules can still see all the symbols they need.
Re: [PATCH 2/2] filemap: Add __filemap_get_folio_mpol()
Posted by Andrew Morton 3 months, 2 weeks ago
On Fri, 20 Jun 2025 17:53:15 +0100 Matthew Wilcox <willy@infradead.org> wrote:

> On Fri, Jun 20, 2025 at 03:34:47PM +0100, Matthew Wilcox (Oracle) wrote:
> > +struct folio *__filemap_get_folio_mpol(struct address_space *mapping,
> > +		pgoff_t index, fgf_t fgp_flags, gfp_t gfp,
> > +		struct mempolicy *policy)
> >  {
> >  	struct folio *folio;
> >  
> > @@ -1982,7 +1984,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
> >  			err = -ENOMEM;
> >  			if (order > min_order)
> >  				alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN;
> > -			folio = filemap_alloc_folio(alloc_gfp, order, NULL);
> > +			folio = filemap_alloc_folio(alloc_gfp, order, policy);
> >  			if (!folio)
> >  				continue;
> 
> This is missing the EXPORT_SYMBOL_GPL() change

I added this:

--- a/mm/filemap.c~filemap-add-__filemap_get_folio_mpol-fix
+++ a/mm/filemap.c
@@ -2032,7 +2032,7 @@ no_page:
 		folio_clear_dropbehind(folio);
 	return folio;
 }
-EXPORT_SYMBOL(__filemap_get_folio);
+EXPORT_SYMBOL(__filemap_get_folio_mpol);
 
 static inline struct folio *find_get_entry(struct xa_state *xas, pgoff_t max,
 		xa_mark_t mark)
_
Re: [PATCH 2/2] filemap: Add __filemap_get_folio_mpol()
Posted by Shivank Garg 3 months, 2 weeks ago

On 6/23/2025 12:13 AM, Andrew Morton wrote:
> On Fri, 20 Jun 2025 17:53:15 +0100 Matthew Wilcox <willy@infradead.org> wrote:
> 
>> On Fri, Jun 20, 2025 at 03:34:47PM +0100, Matthew Wilcox (Oracle) wrote:
>>> +struct folio *__filemap_get_folio_mpol(struct address_space *mapping,
>>> +		pgoff_t index, fgf_t fgp_flags, gfp_t gfp,
>>> +		struct mempolicy *policy)
>>>  {
>>>  	struct folio *folio;
>>>  
>>> @@ -1982,7 +1984,7 @@ struct folio *__filemap_get_folio(struct address_space *mapping, pgoff_t index,
>>>  			err = -ENOMEM;
>>>  			if (order > min_order)
>>>  				alloc_gfp |= __GFP_NORETRY | __GFP_NOWARN;
>>> -			folio = filemap_alloc_folio(alloc_gfp, order, NULL);
>>> +			folio = filemap_alloc_folio(alloc_gfp, order, policy);
>>>  			if (!folio)
>>>  				continue;
>>
>> This is missing the EXPORT_SYMBOL_GPL() change
> 
> I added this:
> 
> --- a/mm/filemap.c~filemap-add-__filemap_get_folio_mpol-fix
> +++ a/mm/filemap.c
> @@ -2032,7 +2032,7 @@ no_page:
>  		folio_clear_dropbehind(folio);
>  	return folio;
>  }
> -EXPORT_SYMBOL(__filemap_get_folio);
> +EXPORT_SYMBOL(__filemap_get_folio_mpol);
>  
>  static inline struct folio *find_get_entry(struct xa_state *xas, pgoff_t max,
>  		xa_mark_t mark)
> _
> 

Hi Andrew,

Thank you for addressing this.

If you don’t mind me asking,
I was curious why we used EXPORT_SYMBOL instead of EXPORT_SYMBOL_GPL here.
I had previously received feedback recommending the use of EXPORT_SYMBOL_GPL
to better align with the kernel’s licensing philosophy, which made sense to me.

Thanks,
Shivank
Re: [PATCH 2/2] filemap: Add __filemap_get_folio_mpol()
Posted by Vlastimil Babka 3 months, 2 weeks ago
On 6/22/25 21:02, Shivank Garg wrote:
> 
> Hi Andrew,
> 
> Thank you for addressing this.
> 
> If you don’t mind me asking,
> I was curious why we used EXPORT_SYMBOL instead of EXPORT_SYMBOL_GPL here.
> I had previously received feedback recommending the use of EXPORT_SYMBOL_GPL
> to better align with the kernel’s licensing philosophy, which made sense to me.

That's the recommendation for new symbols, but this has become effectively a
rename (plus a new parameter) so it's a bit different situation.

> Thanks,
> Shivank
> 

Re: [PATCH 2/2] filemap: Add __filemap_get_folio_mpol()
Posted by Shivank Garg 3 months, 2 weeks ago

On 6/23/2025 12:46 PM, Vlastimil Babka wrote:
> On 6/22/25 21:02, Shivank Garg wrote:
>>
>> Hi Andrew,
>>
>> Thank you for addressing this.
>>
>> If you don’t mind me asking,
>> I was curious why we used EXPORT_SYMBOL instead of EXPORT_SYMBOL_GPL here.
>> I had previously received feedback recommending the use of EXPORT_SYMBOL_GPL
>> to better align with the kernel’s licensing philosophy, which made sense to me.
> 
> That's the recommendation for new symbols, but this has become effectively a
> rename (plus a new parameter) so it's a bit different situation.

agreed, Thanks.
Re: [PATCH 2/2] filemap: Add __filemap_get_folio_mpol()
Posted by Andrew Morton 3 months, 2 weeks ago
On Mon, 23 Jun 2025 00:32:05 +0530 Shivank Garg <shivankg@amd.com> wrote:

> > -EXPORT_SYMBOL(__filemap_get_folio);
> > +EXPORT_SYMBOL(__filemap_get_folio_mpol);
> >  
> >  static inline struct folio *find_get_entry(struct xa_state *xas, pgoff_t max,
> >  		xa_mark_t mark)
> > _
> > 
> 
> Hi Andrew,
> 
> Thank you for addressing this.
> 
> If you don’t mind me asking,
> I was curious why we used EXPORT_SYMBOL instead of EXPORT_SYMBOL_GPL here.
> I had previously received feedback recommending the use of EXPORT_SYMBOL_GPL
> to better align with the kernel’s licensing philosophy, which made sense to me.

Making this _GPL would effectively switch __filemap_get_folio() from
non-GPL to GPL.  Leaving it at non-GPL is less disruptive and Matthew's
patch did not have the intention of changing licensing.

Also,

hp2:/usr/src/25> grep "EXPORT_SYMBOL(" mm/filemap.c|wc -l
48
hp2:/usr/src/25> grep "EXPORT_SYMBOL_GPL(" mm/filemap.c|wc -l 
9


Re: [PATCH 2/2] filemap: Add __filemap_get_folio_mpol()
Posted by Shivank Garg 3 months, 2 weeks ago

On 6/23/2025 3:46 AM, Andrew Morton wrote:
> On Mon, 23 Jun 2025 00:32:05 +0530 Shivank Garg <shivankg@amd.com> wrote:
> 
>>> -EXPORT_SYMBOL(__filemap_get_folio);
>>> +EXPORT_SYMBOL(__filemap_get_folio_mpol);
>>>  
>>>  static inline struct folio *find_get_entry(struct xa_state *xas, pgoff_t max,
>>>  		xa_mark_t mark)
>>> _
>>>
>>
>> Hi Andrew,
>>
>> Thank you for addressing this.
>>
>> If you don’t mind me asking,
>> I was curious why we used EXPORT_SYMBOL instead of EXPORT_SYMBOL_GPL here.
>> I had previously received feedback recommending the use of EXPORT_SYMBOL_GPL
>> to better align with the kernel’s licensing philosophy, which made sense to me.
> 
> Making this _GPL would effectively switch __filemap_get_folio() from
> non-GPL to GPL.  Leaving it at non-GPL is less disruptive and Matthew's
> patch did not have the intention of changing licensing.
> 
> Also,
> 
> hp2:/usr/src/25> grep "EXPORT_SYMBOL(" mm/filemap.c|wc -l
> 48
> hp2:/usr/src/25> grep "EXPORT_SYMBOL_GPL(" mm/filemap.c|wc -l 
> 9
> 
> 

Can you pick these revised patches:

https://lore.kernel.org/linux-mm/20250623093939.1323623-4-shivankg@amd.com

I did some touch-up on commit description, changed some code alignments to make it more readable
and fixed couple of checkpatch.pl warnings.

Thanks,
Shivank
Re: [PATCH 2/2] filemap: Add __filemap_get_folio_mpol()
Posted by Shivank Garg 3 months, 2 weeks ago

On 6/23/2025 3:46 AM, Andrew Morton wrote:
> On Mon, 23 Jun 2025 00:32:05 +0530 Shivank Garg <shivankg@amd.com> wrote:
> 
>>> -EXPORT_SYMBOL(__filemap_get_folio);
>>> +EXPORT_SYMBOL(__filemap_get_folio_mpol);
>>>  
>>>  static inline struct folio *find_get_entry(struct xa_state *xas, pgoff_t max,
>>>  		xa_mark_t mark)
>>> _
>>>
>>
>> Hi Andrew,
>>
>> Thank you for addressing this.
>>
>> If you don’t mind me asking,
>> I was curious why we used EXPORT_SYMBOL instead of EXPORT_SYMBOL_GPL here.
>> I had previously received feedback recommending the use of EXPORT_SYMBOL_GPL
>> to better align with the kernel’s licensing philosophy, which made sense to me.
> 
> Making this _GPL would effectively switch __filemap_get_folio() from
> non-GPL to GPL.  Leaving it at non-GPL is less disruptive and Matthew's
> patch did not have the intention of changing licensing.
> 
> Also,
> 
> hp2:/usr/src/25> grep "EXPORT_SYMBOL(" mm/filemap.c|wc -l
> 48
> hp2:/usr/src/25> grep "EXPORT_SYMBOL_GPL(" mm/filemap.c|wc -l 
> 9
> 
> 

Thank you for the explanation.
This makes sense to me.

Reviewed-by: Shivank Garg <shivankg@amd.com>


Thanks,
Shivank