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* [PATCH 0/3] Minor fixes for memory allocation profiling
@ 2025-09-09 23:34 Suren Baghdasaryan
  2025-09-09 23:34 ` [PATCH 1/3] alloc_tag: use release_pages() in the cleanup path Suren Baghdasaryan
                   ` (2 more replies)
  0 siblings, 3 replies; 15+ messages in thread
From: Suren Baghdasaryan @ 2025-09-09 23:34 UTC (permalink / raw)
  To: akpm
  Cc: kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	usamaarif642, shakeel.butt, 00107082, pasha.tatashin, souravpanda,
	surenb, linux-mm, linux-kernel

Over the last couple months I gathered a few reports of minor issues
in memory allocation profiling which are addressed in this patchset.

Patchset is based on mm-new.

Suren Baghdasaryan (3):
  alloc_tag: use release_pages() in the cleanup path
  alloc_tag: prevent enabling memory profiling if it was shut down
  alloc_tag: avoid warnings when freeing non-compound "tail" pages

 lib/alloc_tag.c | 17 ++++++++++++++---
 mm/page_alloc.c |  9 ++++++++-
 2 files changed, 22 insertions(+), 4 deletions(-)


base-commit: f4e8f46973fe0c0f579944a37e96ba9efbe00cca
-- 
2.51.0.384.g4c02a37b29-goog



^ permalink raw reply	[flat|nested] 15+ messages in thread

* [PATCH 1/3] alloc_tag: use release_pages() in the cleanup path
  2025-09-09 23:34 [PATCH 0/3] Minor fixes for memory allocation profiling Suren Baghdasaryan
@ 2025-09-09 23:34 ` Suren Baghdasaryan
  2025-09-10  5:31   ` Shakeel Butt
  2025-09-10 20:49   ` Usama Arif
  2025-09-09 23:34 ` [PATCH 2/3] alloc_tag: prevent enabling memory profiling if it was shut down Suren Baghdasaryan
  2025-09-09 23:34 ` [PATCH 3/3] alloc_tag: avoid warnings when freeing non-compound "tail" pages Suren Baghdasaryan
  2 siblings, 2 replies; 15+ messages in thread
From: Suren Baghdasaryan @ 2025-09-09 23:34 UTC (permalink / raw)
  To: akpm
  Cc: kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	usamaarif642, shakeel.butt, 00107082, pasha.tatashin, souravpanda,
	surenb, linux-mm, linux-kernel

When bulk-freeing an array of pages use release_pages() instead of freeing
them page-by-page:

Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 lib/alloc_tag.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
index e9b33848700a..95688c4cba7a 100644
--- a/lib/alloc_tag.c
+++ b/lib/alloc_tag.c
@@ -438,9 +438,10 @@ static int vm_module_tags_populate(void)
 		if (nr < more_pages ||
 		    vmap_pages_range(phys_end, phys_end + (nr << PAGE_SHIFT), PAGE_KERNEL,
 				     next_page, PAGE_SHIFT) < 0) {
+			release_pages_arg arg = { .pages = next_page };
+
 			/* Clean up and error out */
-			for (int i = 0; i < nr; i++)
-				__free_page(next_page[i]);
+			release_pages(arg, nr);
 			return -ENOMEM;
 		}
 
-- 
2.51.0.384.g4c02a37b29-goog



^ permalink raw reply related	[flat|nested] 15+ messages in thread

* [PATCH 2/3] alloc_tag: prevent enabling memory profiling if it was shut down
  2025-09-09 23:34 [PATCH 0/3] Minor fixes for memory allocation profiling Suren Baghdasaryan
  2025-09-09 23:34 ` [PATCH 1/3] alloc_tag: use release_pages() in the cleanup path Suren Baghdasaryan
@ 2025-09-09 23:34 ` Suren Baghdasaryan
  2025-09-10  5:32   ` Shakeel Butt
  2025-09-10 20:51   ` Usama Arif
  2025-09-09 23:34 ` [PATCH 3/3] alloc_tag: avoid warnings when freeing non-compound "tail" pages Suren Baghdasaryan
  2 siblings, 2 replies; 15+ messages in thread
From: Suren Baghdasaryan @ 2025-09-09 23:34 UTC (permalink / raw)
  To: akpm
  Cc: kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	usamaarif642, shakeel.butt, 00107082, pasha.tatashin, souravpanda,
	surenb, linux-mm, linux-kernel

Memory profiling can be shut down due to reasons like a failure during
initialization. When this happens, the user should not be able to
re-enable it. Current sysctrl interface does not handle this properly
and will allow re-enabling memory profiling. Fix this by checking for
this condition during sysctrl write operation.

Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 lib/alloc_tag.c | 12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
index 95688c4cba7a..79891528e7b6 100644
--- a/lib/alloc_tag.c
+++ b/lib/alloc_tag.c
@@ -767,6 +767,16 @@ struct page_ext_operations page_alloc_tagging_ops = {
 EXPORT_SYMBOL(page_alloc_tagging_ops);
 
 #ifdef CONFIG_SYSCTL
+static int proc_mem_profiling_handler(const struct ctl_table *table, int write,
+				      void *buffer, size_t *lenp, loff_t *ppos)
+{
+	if (!mem_profiling_support && write)
+		return -EINVAL;
+
+	return proc_do_static_key(table, write, buffer, lenp, ppos);
+}
+
+
 static struct ctl_table memory_allocation_profiling_sysctls[] = {
 	{
 		.procname	= "mem_profiling",
@@ -776,7 +786,7 @@ static struct ctl_table memory_allocation_profiling_sysctls[] = {
 #else
 		.mode		= 0644,
 #endif
-		.proc_handler	= proc_do_static_key,
+		.proc_handler	= proc_mem_profiling_handler,
 	},
 };
 
-- 
2.51.0.384.g4c02a37b29-goog



^ permalink raw reply related	[flat|nested] 15+ messages in thread

* [PATCH 3/3] alloc_tag: avoid warnings when freeing non-compound "tail" pages
  2025-09-09 23:34 [PATCH 0/3] Minor fixes for memory allocation profiling Suren Baghdasaryan
  2025-09-09 23:34 ` [PATCH 1/3] alloc_tag: use release_pages() in the cleanup path Suren Baghdasaryan
  2025-09-09 23:34 ` [PATCH 2/3] alloc_tag: prevent enabling memory profiling if it was shut down Suren Baghdasaryan
@ 2025-09-09 23:34 ` Suren Baghdasaryan
  2025-09-11 20:01   ` Shakeel Butt
  2025-09-11 22:58   ` Shakeel Butt
  2 siblings, 2 replies; 15+ messages in thread
From: Suren Baghdasaryan @ 2025-09-09 23:34 UTC (permalink / raw)
  To: akpm
  Cc: kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	usamaarif642, shakeel.butt, 00107082, pasha.tatashin, souravpanda,
	surenb, linux-mm, linux-kernel

When freeing "tail" pages of a non-compount high-order page, we properly
subtract the allocation tag counters, however later when these pages are
released, alloc_tag_sub() will issue warnings because tags for these pages
are NULL.
This issue was originally anticipated by Vlastimil in his review [1] and
then recently reported by David.
Prevent warnings by marking the tags empty.

[1] https://lore.kernel.org/all/6db0f0c8-81cb-4d04-9560-ba73d63db4b8@suse.cz/

Suggested-by: David Wang <00107082@163.com>
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
---
 mm/page_alloc.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 1760346bbd24..d21a411e807e 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -5240,9 +5240,16 @@ static void ___free_pages(struct page *page, unsigned int order,
 		__free_frozen_pages(page, order, fpi_flags);
 	else if (!head) {
 		pgalloc_tag_sub_pages(tag, (1 << order) - 1);
-		while (order-- > 0)
+		while (order-- > 0) {
+			/*
+			 * The "tail" pages of this non-compound high-order
+			 * page will have no code tags, so to avoid warnings
+			 * mark them as empty.
+			 */
+			clear_page_tag_ref(page + (1 << order));
 			__free_frozen_pages(page + (1 << order), order,
 					    fpi_flags);
+		}
 	}
 }
 
-- 
2.51.0.384.g4c02a37b29-goog



^ permalink raw reply related	[flat|nested] 15+ messages in thread

* Re: [PATCH 1/3] alloc_tag: use release_pages() in the cleanup path
  2025-09-09 23:34 ` [PATCH 1/3] alloc_tag: use release_pages() in the cleanup path Suren Baghdasaryan
@ 2025-09-10  5:31   ` Shakeel Butt
  2025-09-10 20:49   ` Usama Arif
  1 sibling, 0 replies; 15+ messages in thread
From: Shakeel Butt @ 2025-09-10  5:31 UTC (permalink / raw)
  To: Suren Baghdasaryan
  Cc: akpm, kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	usamaarif642, 00107082, pasha.tatashin, souravpanda, linux-mm,
	linux-kernel

On Tue, Sep 09, 2025 at 04:34:07PM -0700, Suren Baghdasaryan wrote:
> When bulk-freeing an array of pages use release_pages() instead of freeing
> them page-by-page:
> 
> Suggested-by: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>

Acked-by: Shakeel Butt <shakeel.butt@linux.dev>


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 2/3] alloc_tag: prevent enabling memory profiling if it was shut down
  2025-09-09 23:34 ` [PATCH 2/3] alloc_tag: prevent enabling memory profiling if it was shut down Suren Baghdasaryan
@ 2025-09-10  5:32   ` Shakeel Butt
  2025-09-10 20:51   ` Usama Arif
  1 sibling, 0 replies; 15+ messages in thread
From: Shakeel Butt @ 2025-09-10  5:32 UTC (permalink / raw)
  To: Suren Baghdasaryan
  Cc: akpm, kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	usamaarif642, 00107082, pasha.tatashin, souravpanda, linux-mm,
	linux-kernel

On Tue, Sep 09, 2025 at 04:34:08PM -0700, Suren Baghdasaryan wrote:
> Memory profiling can be shut down due to reasons like a failure during
> initialization. When this happens, the user should not be able to
> re-enable it. Current sysctrl interface does not handle this properly
> and will allow re-enabling memory profiling. Fix this by checking for
> this condition during sysctrl write operation.
> 
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>

Acked-by: Shakeel Butt <shakeel.butt@linux.dev>


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 1/3] alloc_tag: use release_pages() in the cleanup path
  2025-09-09 23:34 ` [PATCH 1/3] alloc_tag: use release_pages() in the cleanup path Suren Baghdasaryan
  2025-09-10  5:31   ` Shakeel Butt
@ 2025-09-10 20:49   ` Usama Arif
  2025-09-12 21:05     ` Suren Baghdasaryan
  1 sibling, 1 reply; 15+ messages in thread
From: Usama Arif @ 2025-09-10 20:49 UTC (permalink / raw)
  To: Suren Baghdasaryan, akpm
  Cc: kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	shakeel.butt, 00107082, pasha.tatashin, souravpanda, linux-mm,
	linux-kernel



On 10/09/2025 00:34, Suren Baghdasaryan wrote:
> When bulk-freeing an array of pages use release_pages() instead of freeing
> them page-by-page:
> 
> Suggested-by: Andrew Morton <akpm@linux-foundation.org>
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> ---
>  lib/alloc_tag.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 

Acked-by: Usama Arif <usamaarif642@gmail.com>

> diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
> index e9b33848700a..95688c4cba7a 100644
> --- a/lib/alloc_tag.c
> +++ b/lib/alloc_tag.c
> @@ -438,9 +438,10 @@ static int vm_module_tags_populate(void)
>  		if (nr < more_pages ||
>  		    vmap_pages_range(phys_end, phys_end + (nr << PAGE_SHIFT), PAGE_KERNEL,
>  				     next_page, PAGE_SHIFT) < 0) {
> +			release_pages_arg arg = { .pages = next_page };
> +
>  			/* Clean up and error out */
> -			for (int i = 0; i < nr; i++)
> -				__free_page(next_page[i]);
> +			release_pages(arg, nr);
>  			return -ENOMEM;
>  		}
>  

Maybe this can be done in free_mod_tags_mem as well?


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 2/3] alloc_tag: prevent enabling memory profiling if it was shut down
  2025-09-09 23:34 ` [PATCH 2/3] alloc_tag: prevent enabling memory profiling if it was shut down Suren Baghdasaryan
  2025-09-10  5:32   ` Shakeel Butt
@ 2025-09-10 20:51   ` Usama Arif
  2025-09-11 17:01     ` Suren Baghdasaryan
  1 sibling, 1 reply; 15+ messages in thread
From: Usama Arif @ 2025-09-10 20:51 UTC (permalink / raw)
  To: Suren Baghdasaryan, akpm
  Cc: kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	shakeel.butt, 00107082, pasha.tatashin, souravpanda, linux-mm,
	linux-kernel



On 10/09/2025 00:34, Suren Baghdasaryan wrote:
> Memory profiling can be shut down due to reasons like a failure during
> initialization. When this happens, the user should not be able to
> re-enable it. Current sysctrl interface does not handle this properly
> and will allow re-enabling memory profiling. Fix this by checking for
> this condition during sysctrl write operation.
> 
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> ---
>  lib/alloc_tag.c | 12 +++++++++++-
>  1 file changed, 11 insertions(+), 1 deletion(-)
> 

Acked-by: Usama Arif <usamaarif642@gmail.com>



> diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
> index 95688c4cba7a..79891528e7b6 100644
> --- a/lib/alloc_tag.c
> +++ b/lib/alloc_tag.c
> @@ -767,6 +767,16 @@ struct page_ext_operations page_alloc_tagging_ops = {
>  EXPORT_SYMBOL(page_alloc_tagging_ops);
>  
>  #ifdef CONFIG_SYSCTL

nit: might be good to add a comment here that we are not using default as we dont want to enable
it back if it fails once. But not worth a respin as someone can always check git log if curious.

> +static int proc_mem_profiling_handler(const struct ctl_table *table, int write,
> +				      void *buffer, size_t *lenp, loff_t *ppos)
> +{
> +	if (!mem_profiling_support && write)
> +		return -EINVAL;
> +
> +	return proc_do_static_key(table, write, buffer, lenp, ppos);
> +}
> +
> +
>  static struct ctl_table memory_allocation_profiling_sysctls[] = {
>  	{
>  		.procname	= "mem_profiling",
> @@ -776,7 +786,7 @@ static struct ctl_table memory_allocation_profiling_sysctls[] = {
>  #else
>  		.mode		= 0644,
>  #endif
> -		.proc_handler	= proc_do_static_key,
> +		.proc_handler	= proc_mem_profiling_handler,
>  	},
>  };
>  



^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 2/3] alloc_tag: prevent enabling memory profiling if it was shut down
  2025-09-10 20:51   ` Usama Arif
@ 2025-09-11 17:01     ` Suren Baghdasaryan
  0 siblings, 0 replies; 15+ messages in thread
From: Suren Baghdasaryan @ 2025-09-11 17:01 UTC (permalink / raw)
  To: Usama Arif
  Cc: akpm, kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	shakeel.butt, 00107082, pasha.tatashin, souravpanda, linux-mm,
	linux-kernel

On Wed, Sep 10, 2025 at 1:52 PM Usama Arif <usamaarif642@gmail.com> wrote:
>
>
>
> On 10/09/2025 00:34, Suren Baghdasaryan wrote:
> > Memory profiling can be shut down due to reasons like a failure during
> > initialization. When this happens, the user should not be able to
> > re-enable it. Current sysctrl interface does not handle this properly
> > and will allow re-enabling memory profiling. Fix this by checking for
> > this condition during sysctrl write operation.
> >
> > Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> > ---
> >  lib/alloc_tag.c | 12 +++++++++++-
> >  1 file changed, 11 insertions(+), 1 deletion(-)
> >
>
> Acked-by: Usama Arif <usamaarif642@gmail.com>
>
>
>
> > diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
> > index 95688c4cba7a..79891528e7b6 100644
> > --- a/lib/alloc_tag.c
> > +++ b/lib/alloc_tag.c
> > @@ -767,6 +767,16 @@ struct page_ext_operations page_alloc_tagging_ops = {
> >  EXPORT_SYMBOL(page_alloc_tagging_ops);
> >
> >  #ifdef CONFIG_SYSCTL
>
> nit: might be good to add a comment here that we are not using default as we dont want to enable
> it back if it fails once. But not worth a respin as someone can always check git log if curious.

Ok, if I respin the series will add it. Thanks!

>
> > +static int proc_mem_profiling_handler(const struct ctl_table *table, int write,
> > +                                   void *buffer, size_t *lenp, loff_t *ppos)
> > +{
> > +     if (!mem_profiling_support && write)
> > +             return -EINVAL;
> > +
> > +     return proc_do_static_key(table, write, buffer, lenp, ppos);
> > +}
> > +
> > +
> >  static struct ctl_table memory_allocation_profiling_sysctls[] = {
> >       {
> >               .procname       = "mem_profiling",
> > @@ -776,7 +786,7 @@ static struct ctl_table memory_allocation_profiling_sysctls[] = {
> >  #else
> >               .mode           = 0644,
> >  #endif
> > -             .proc_handler   = proc_do_static_key,
> > +             .proc_handler   = proc_mem_profiling_handler,
> >       },
> >  };
> >
>


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 3/3] alloc_tag: avoid warnings when freeing non-compound "tail" pages
  2025-09-09 23:34 ` [PATCH 3/3] alloc_tag: avoid warnings when freeing non-compound "tail" pages Suren Baghdasaryan
@ 2025-09-11 20:01   ` Shakeel Butt
  2025-09-11 20:12     ` Suren Baghdasaryan
  2025-09-11 22:58   ` Shakeel Butt
  1 sibling, 1 reply; 15+ messages in thread
From: Shakeel Butt @ 2025-09-11 20:01 UTC (permalink / raw)
  To: Suren Baghdasaryan
  Cc: akpm, kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	usamaarif642, 00107082, pasha.tatashin, souravpanda, linux-mm,
	linux-kernel

On Tue, Sep 09, 2025 at 04:34:09PM -0700, Suren Baghdasaryan wrote:
> When freeing "tail" pages of a non-compount high-order page, we properly
> subtract the allocation tag counters, however later when these pages are
> released, alloc_tag_sub() will issue warnings because tags for these pages
> are NULL.
> This issue was originally anticipated by Vlastimil in his review [1] and
> then recently reported by David.
> Prevent warnings by marking the tags empty.
> 
> [1] https://lore.kernel.org/all/6db0f0c8-81cb-4d04-9560-ba73d63db4b8@suse.cz/
> 
> Suggested-by: David Wang <00107082@163.com>
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> ---
>  mm/page_alloc.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 1760346bbd24..d21a411e807e 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -5240,9 +5240,16 @@ static void ___free_pages(struct page *page, unsigned int order,
>  		__free_frozen_pages(page, order, fpi_flags);
>  	else if (!head) {
>  		pgalloc_tag_sub_pages(tag, (1 << order) - 1);
> -		while (order-- > 0)
> +		while (order-- > 0) {
> +			/*
> +			 * The "tail" pages of this non-compound high-order
> +			 * page will have no code tags, so to avoid warnings
> +			 * mark them as empty.
> +			 */
> +			clear_page_tag_ref(page + (1 << order));

Do we need something similar for the release_pages() code path or is it
happening already?

>  			__free_frozen_pages(page + (1 << order), order,
>  					    fpi_flags);
> +		}
>  	}
>  }
>  
> -- 
> 2.51.0.384.g4c02a37b29-goog
> 


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 3/3] alloc_tag: avoid warnings when freeing non-compound "tail" pages
  2025-09-11 20:01   ` Shakeel Butt
@ 2025-09-11 20:12     ` Suren Baghdasaryan
  2025-09-11 21:44       ` Shakeel Butt
  0 siblings, 1 reply; 15+ messages in thread
From: Suren Baghdasaryan @ 2025-09-11 20:12 UTC (permalink / raw)
  To: Shakeel Butt
  Cc: akpm, kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	usamaarif642, 00107082, pasha.tatashin, souravpanda, linux-mm,
	linux-kernel

On Thu, Sep 11, 2025 at 1:01 PM Shakeel Butt <shakeel.butt@linux.dev> wrote:
>
> On Tue, Sep 09, 2025 at 04:34:09PM -0700, Suren Baghdasaryan wrote:
> > When freeing "tail" pages of a non-compount high-order page, we properly
> > subtract the allocation tag counters, however later when these pages are
> > released, alloc_tag_sub() will issue warnings because tags for these pages
> > are NULL.
> > This issue was originally anticipated by Vlastimil in his review [1] and
> > then recently reported by David.
> > Prevent warnings by marking the tags empty.
> >
> > [1] https://lore.kernel.org/all/6db0f0c8-81cb-4d04-9560-ba73d63db4b8@suse.cz/
> >
> > Suggested-by: David Wang <00107082@163.com>
> > Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> > ---
> >  mm/page_alloc.c | 9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > index 1760346bbd24..d21a411e807e 100644
> > --- a/mm/page_alloc.c
> > +++ b/mm/page_alloc.c
> > @@ -5240,9 +5240,16 @@ static void ___free_pages(struct page *page, unsigned int order,
> >               __free_frozen_pages(page, order, fpi_flags);
> >       else if (!head) {
> >               pgalloc_tag_sub_pages(tag, (1 << order) - 1);
> > -             while (order-- > 0)
> > +             while (order-- > 0) {
> > +                     /*
> > +                      * The "tail" pages of this non-compound high-order
> > +                      * page will have no code tags, so to avoid warnings
> > +                      * mark them as empty.
> > +                      */
> > +                     clear_page_tag_ref(page + (1 << order));
>
> Do we need something similar for the release_pages() code path or is it
> happening already?

Pages released with release_pages() should have valid tags, so I
expect no warnings.

>
> >                       __free_frozen_pages(page + (1 << order), order,
> >                                           fpi_flags);
> > +             }
> >       }
> >  }
> >
> > --
> > 2.51.0.384.g4c02a37b29-goog
> >
>


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 3/3] alloc_tag: avoid warnings when freeing non-compound "tail" pages
  2025-09-11 20:12     ` Suren Baghdasaryan
@ 2025-09-11 21:44       ` Shakeel Butt
  2025-09-11 21:51         ` Suren Baghdasaryan
  0 siblings, 1 reply; 15+ messages in thread
From: Shakeel Butt @ 2025-09-11 21:44 UTC (permalink / raw)
  To: Suren Baghdasaryan
  Cc: akpm, kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	usamaarif642, 00107082, pasha.tatashin, souravpanda, linux-mm,
	linux-kernel

On Thu, Sep 11, 2025 at 01:12:11PM -0700, Suren Baghdasaryan wrote:
> On Thu, Sep 11, 2025 at 1:01 PM Shakeel Butt <shakeel.butt@linux.dev> wrote:
> >
> > On Tue, Sep 09, 2025 at 04:34:09PM -0700, Suren Baghdasaryan wrote:
> > > When freeing "tail" pages of a non-compount high-order page, we properly
> > > subtract the allocation tag counters, however later when these pages are
> > > released, alloc_tag_sub() will issue warnings because tags for these pages
> > > are NULL.
> > > This issue was originally anticipated by Vlastimil in his review [1] and
> > > then recently reported by David.
> > > Prevent warnings by marking the tags empty.
> > >
> > > [1] https://lore.kernel.org/all/6db0f0c8-81cb-4d04-9560-ba73d63db4b8@suse.cz/
> > >
> > > Suggested-by: David Wang <00107082@163.com>
> > > Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> > > ---
> > >  mm/page_alloc.c | 9 ++++++++-
> > >  1 file changed, 8 insertions(+), 1 deletion(-)
> > >
> > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > > index 1760346bbd24..d21a411e807e 100644
> > > --- a/mm/page_alloc.c
> > > +++ b/mm/page_alloc.c
> > > @@ -5240,9 +5240,16 @@ static void ___free_pages(struct page *page, unsigned int order,
> > >               __free_frozen_pages(page, order, fpi_flags);
> > >       else if (!head) {
> > >               pgalloc_tag_sub_pages(tag, (1 << order) - 1);
> > > -             while (order-- > 0)
> > > +             while (order-- > 0) {
> > > +                     /*
> > > +                      * The "tail" pages of this non-compound high-order
> > > +                      * page will have no code tags, so to avoid warnings
> > > +                      * mark them as empty.
> > > +                      */
> > > +                     clear_page_tag_ref(page + (1 << order));
> >
> > Do we need something similar for the release_pages() code path or is it
> > happening already?
> 
> Pages released with release_pages() should have valid tags, so I
> expect no warnings.
> 

Oh so this is orthogonal to your first patch which is replacing
__free_page with release_pages(). This non-compound high-order page is
not an issue in the codepath vm_module_tags_populate(), correct?


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 3/3] alloc_tag: avoid warnings when freeing non-compound "tail" pages
  2025-09-11 21:44       ` Shakeel Butt
@ 2025-09-11 21:51         ` Suren Baghdasaryan
  0 siblings, 0 replies; 15+ messages in thread
From: Suren Baghdasaryan @ 2025-09-11 21:51 UTC (permalink / raw)
  To: Shakeel Butt
  Cc: akpm, kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	usamaarif642, 00107082, pasha.tatashin, souravpanda, linux-mm,
	linux-kernel

On Thu, Sep 11, 2025 at 2:45 PM Shakeel Butt <shakeel.butt@linux.dev> wrote:
>
> On Thu, Sep 11, 2025 at 01:12:11PM -0700, Suren Baghdasaryan wrote:
> > On Thu, Sep 11, 2025 at 1:01 PM Shakeel Butt <shakeel.butt@linux.dev> wrote:
> > >
> > > On Tue, Sep 09, 2025 at 04:34:09PM -0700, Suren Baghdasaryan wrote:
> > > > When freeing "tail" pages of a non-compount high-order page, we properly
> > > > subtract the allocation tag counters, however later when these pages are
> > > > released, alloc_tag_sub() will issue warnings because tags for these pages
> > > > are NULL.
> > > > This issue was originally anticipated by Vlastimil in his review [1] and
> > > > then recently reported by David.
> > > > Prevent warnings by marking the tags empty.
> > > >
> > > > [1] https://lore.kernel.org/all/6db0f0c8-81cb-4d04-9560-ba73d63db4b8@suse.cz/
> > > >
> > > > Suggested-by: David Wang <00107082@163.com>
> > > > Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> > > > ---
> > > >  mm/page_alloc.c | 9 ++++++++-
> > > >  1 file changed, 8 insertions(+), 1 deletion(-)
> > > >
> > > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> > > > index 1760346bbd24..d21a411e807e 100644
> > > > --- a/mm/page_alloc.c
> > > > +++ b/mm/page_alloc.c
> > > > @@ -5240,9 +5240,16 @@ static void ___free_pages(struct page *page, unsigned int order,
> > > >               __free_frozen_pages(page, order, fpi_flags);
> > > >       else if (!head) {
> > > >               pgalloc_tag_sub_pages(tag, (1 << order) - 1);
> > > > -             while (order-- > 0)
> > > > +             while (order-- > 0) {
> > > > +                     /*
> > > > +                      * The "tail" pages of this non-compound high-order
> > > > +                      * page will have no code tags, so to avoid warnings
> > > > +                      * mark them as empty.
> > > > +                      */
> > > > +                     clear_page_tag_ref(page + (1 << order));
> > >
> > > Do we need something similar for the release_pages() code path or is it
> > > happening already?
> >
> > Pages released with release_pages() should have valid tags, so I
> > expect no warnings.
> >
>
> Oh so this is orthogonal to your first patch which is replacing
> __free_page with release_pages(). This non-compound high-order page is
> not an issue in the codepath vm_module_tags_populate(), correct?

Yes, these are independent fixes.


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 3/3] alloc_tag: avoid warnings when freeing non-compound "tail" pages
  2025-09-09 23:34 ` [PATCH 3/3] alloc_tag: avoid warnings when freeing non-compound "tail" pages Suren Baghdasaryan
  2025-09-11 20:01   ` Shakeel Butt
@ 2025-09-11 22:58   ` Shakeel Butt
  1 sibling, 0 replies; 15+ messages in thread
From: Shakeel Butt @ 2025-09-11 22:58 UTC (permalink / raw)
  To: Suren Baghdasaryan
  Cc: akpm, kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	usamaarif642, 00107082, pasha.tatashin, souravpanda, linux-mm,
	linux-kernel

On Tue, Sep 09, 2025 at 04:34:09PM -0700, Suren Baghdasaryan wrote:
> When freeing "tail" pages of a non-compount high-order page, we properly
> subtract the allocation tag counters, however later when these pages are
> released, alloc_tag_sub() will issue warnings because tags for these pages
> are NULL.
> This issue was originally anticipated by Vlastimil in his review [1] and
> then recently reported by David.
> Prevent warnings by marking the tags empty.
> 
> [1] https://lore.kernel.org/all/6db0f0c8-81cb-4d04-9560-ba73d63db4b8@suse.cz/
> 
> Suggested-by: David Wang <00107082@163.com>
> Signed-off-by: Suren Baghdasaryan <surenb@google.com>

Acked-by: Shakeel Butt <shakeel.butt@linux.dev>


^ permalink raw reply	[flat|nested] 15+ messages in thread

* Re: [PATCH 1/3] alloc_tag: use release_pages() in the cleanup path
  2025-09-10 20:49   ` Usama Arif
@ 2025-09-12 21:05     ` Suren Baghdasaryan
  0 siblings, 0 replies; 15+ messages in thread
From: Suren Baghdasaryan @ 2025-09-12 21:05 UTC (permalink / raw)
  To: Usama Arif
  Cc: akpm, kent.overstreet, vbabka, mhocko, jackmanb, hannes, ziy,
	shakeel.butt, 00107082, pasha.tatashin, souravpanda, linux-mm,
	linux-kernel

On Wed, Sep 10, 2025 at 1:49 PM Usama Arif <usamaarif642@gmail.com> wrote:
>
>
>
> On 10/09/2025 00:34, Suren Baghdasaryan wrote:
> > When bulk-freeing an array of pages use release_pages() instead of freeing
> > them page-by-page:
> >
> > Suggested-by: Andrew Morton <akpm@linux-foundation.org>
> > Signed-off-by: Suren Baghdasaryan <surenb@google.com>
> > ---
> >  lib/alloc_tag.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
>
> Acked-by: Usama Arif <usamaarif642@gmail.com>
>
> > diff --git a/lib/alloc_tag.c b/lib/alloc_tag.c
> > index e9b33848700a..95688c4cba7a 100644
> > --- a/lib/alloc_tag.c
> > +++ b/lib/alloc_tag.c
> > @@ -438,9 +438,10 @@ static int vm_module_tags_populate(void)
> >               if (nr < more_pages ||
> >                   vmap_pages_range(phys_end, phys_end + (nr << PAGE_SHIFT), PAGE_KERNEL,
> >                                    next_page, PAGE_SHIFT) < 0) {
> > +                     release_pages_arg arg = { .pages = next_page };
> > +
> >                       /* Clean up and error out */
> > -                     for (int i = 0; i < nr; i++)
> > -                             __free_page(next_page[i]);
> > +                     release_pages(arg, nr);
> >                       return -ENOMEM;
> >               }
> >
>
> Maybe this can be done in free_mod_tags_mem as well?

Good point. I think I will respin this patchset with your suggestions
and will include one more fix for an issue that Shakeel just reported
(see https://lore.kernel.org/all/CAJuCfpGUjaZcs1r9ADKck_Ni7f41kHaiejR01Z0bE8pG0K1uXA@mail.gmail.com/).
Thanks!
Suren.


^ permalink raw reply	[flat|nested] 15+ messages in thread

end of thread, other threads:[~2025-09-12 21:05 UTC | newest]

Thread overview: 15+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2025-09-09 23:34 [PATCH 0/3] Minor fixes for memory allocation profiling Suren Baghdasaryan
2025-09-09 23:34 ` [PATCH 1/3] alloc_tag: use release_pages() in the cleanup path Suren Baghdasaryan
2025-09-10  5:31   ` Shakeel Butt
2025-09-10 20:49   ` Usama Arif
2025-09-12 21:05     ` Suren Baghdasaryan
2025-09-09 23:34 ` [PATCH 2/3] alloc_tag: prevent enabling memory profiling if it was shut down Suren Baghdasaryan
2025-09-10  5:32   ` Shakeel Butt
2025-09-10 20:51   ` Usama Arif
2025-09-11 17:01     ` Suren Baghdasaryan
2025-09-09 23:34 ` [PATCH 3/3] alloc_tag: avoid warnings when freeing non-compound "tail" pages Suren Baghdasaryan
2025-09-11 20:01   ` Shakeel Butt
2025-09-11 20:12     ` Suren Baghdasaryan
2025-09-11 21:44       ` Shakeel Butt
2025-09-11 21:51         ` Suren Baghdasaryan
2025-09-11 22:58   ` Shakeel Butt

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