diff mbox series

[4/7] mm, pagemap: remove SLOB and SLQB from comments and documentation

Message ID 20230310103210.22372-5-vbabka@suse.cz (mailing list archive)
State New
Headers show
Series remove SLOB and allow kfree() with kmem_cache_alloc() | expand

Commit Message

Vlastimil Babka March 10, 2023, 10:32 a.m. UTC 
SLOB has been removed and SLQB never merged, so remove their mentions
from comments and documentation of pagemap.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
 Documentation/admin-guide/mm/pagemap.rst | 6 +++---
 fs/proc/page.c                           | 5 ++---
 2 files changed, 5 insertions(+), 6 deletions(-)

Comments

Hyeonggon Yoo March 14, 2023, 8:19 a.m. UTC | #1 
On Fri, Mar 10, 2023 at 11:32:06AM +0100, Vlastimil Babka wrote:
> SLOB has been removed and SLQB never merged, so remove their mentions
> from comments and documentation of pagemap.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> ---
>  Documentation/admin-guide/mm/pagemap.rst | 6 +++---
>  fs/proc/page.c                           | 5 ++---
>  2 files changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst
> index b5f970dc91e7..bb4aa897a773 100644
> --- a/Documentation/admin-guide/mm/pagemap.rst
> +++ b/Documentation/admin-guide/mm/pagemap.rst
> @@ -91,9 +91,9 @@ Short descriptions to the page flags
>     The page is being locked for exclusive access, e.g. by undergoing read/write
>     IO.
>  7 - SLAB
> -   The page is managed by the SLAB/SLOB/SLUB/SLQB kernel memory allocator.
> -   When compound page is used, SLUB/SLQB will only set this flag on the head
> -   page; SLOB will not flag it at all.
> +   The page is managed by the SLAB/SLUB kernel memory allocator.
> +   When compound page is used, either will only set this flag on the head
> +   page..
>  10 - BUDDY
>      A free memory block managed by the buddy system allocator.
>      The buddy system organizes free memory in blocks of various orders.
> diff --git a/fs/proc/page.c b/fs/proc/page.c
> index 6249c347809a..1356aeffd8dc 100644
> --- a/fs/proc/page.c
> +++ b/fs/proc/page.c
> @@ -125,7 +125,7 @@ u64 stable_page_flags(struct page *page)
>  	/*
>  	 * pseudo flags for the well known (anonymous) memory mapped pages
>  	 *
> -	 * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
> +	 * Note that page->_mapcount is overloaded in SLAB/SLUB, so the

SLUB does not overload _mapcount.

>  	 * simple test in page_mapped() is not enough.
>  	 */
>  	if (!PageSlab(page) && page_mapped(page))
> @@ -166,8 +166,7 @@ u64 stable_page_flags(struct page *page)
>  
>  	/*
>  	 * Caveats on high order pages: page->_refcount will only be set
> -	 * -1 on the head page; SLUB/SLQB do the same for PG_slab;
> -	 * SLOB won't set PG_slab at all on compound pages.
> +	 * -1 on the head page; SLAB/SLUB do the same for PG_slab;

I think this comment could be just saying that PG_buddy is only set on
head page, not saying

_refcount is set to -1 on head page (is it even correct?)

>  	 */
>  	if (PageBuddy(page))
>  		u |= 1 << KPF_BUDDY;
> -- 
> 2.39.2
>
Lorenzo Stoakes March 14, 2023, 10:16 p.m. UTC | #2 
On Fri, Mar 10, 2023 at 11:32:06AM +0100, Vlastimil Babka wrote:
> SLOB has been removed and SLQB never merged, so remove their mentions
> from comments and documentation of pagemap.
>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> ---
>  Documentation/admin-guide/mm/pagemap.rst | 6 +++---
>  fs/proc/page.c                           | 5 ++---
>  2 files changed, 5 insertions(+), 6 deletions(-)
>
> diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst
> index b5f970dc91e7..bb4aa897a773 100644
> --- a/Documentation/admin-guide/mm/pagemap.rst
> +++ b/Documentation/admin-guide/mm/pagemap.rst
> @@ -91,9 +91,9 @@ Short descriptions to the page flags
>     The page is being locked for exclusive access, e.g. by undergoing read/write
>     IO.
>  7 - SLAB
> -   The page is managed by the SLAB/SLOB/SLUB/SLQB kernel memory allocator.
> -   When compound page is used, SLUB/SLQB will only set this flag on the head
> -   page; SLOB will not flag it at all.
> +   The page is managed by the SLAB/SLUB kernel memory allocator.
> +   When compound page is used, either will only set this flag on the head
> +   page..

I mean, perhaps the nittiest of nits but probably that '..' is unintended.

>  10 - BUDDY
>      A free memory block managed by the buddy system allocator.
>      The buddy system organizes free memory in blocks of various orders.
> diff --git a/fs/proc/page.c b/fs/proc/page.c
> index 6249c347809a..1356aeffd8dc 100644
> --- a/fs/proc/page.c
> +++ b/fs/proc/page.c
> @@ -125,7 +125,7 @@ u64 stable_page_flags(struct page *page)
>  	/*
>  	 * pseudo flags for the well known (anonymous) memory mapped pages
>  	 *
> -	 * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
> +	 * Note that page->_mapcount is overloaded in SLAB/SLUB, so the
>  	 * simple test in page_mapped() is not enough.
>  	 */
>  	if (!PageSlab(page) && page_mapped(page))
> @@ -166,8 +166,7 @@ u64 stable_page_flags(struct page *page)
>
>  	/*
>  	 * Caveats on high order pages: page->_refcount will only be set
> -	 * -1 on the head page; SLUB/SLQB do the same for PG_slab;
> -	 * SLOB won't set PG_slab at all on compound pages.
> +	 * -1 on the head page; SLAB/SLUB do the same for PG_slab;

Nice catch on the redundant reference to the mysterous SLQB (+ above) :)

>  	 */
>  	if (PageBuddy(page))
>  		u |= 1 << KPF_BUDDY;
> --
> 2.39.2
>

Otherwise looks good to me,

Acked-by: Lorenzo Stoakes <lstoakes@gmail.com>
Vlastimil Babka March 15, 2023, 11:05 a.m. UTC | #3 
On 3/14/23 09:19, Hyeonggon Yoo wrote:
> On Fri, Mar 10, 2023 at 11:32:06AM +0100, Vlastimil Babka wrote:
>> SLOB has been removed and SLQB never merged, so remove their mentions
>> from comments and documentation of pagemap.
>> 
>> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
>> ---
>>  Documentation/admin-guide/mm/pagemap.rst | 6 +++---
>>  fs/proc/page.c                           | 5 ++---
>>  2 files changed, 5 insertions(+), 6 deletions(-)
>> 
>> diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst
>> index b5f970dc91e7..bb4aa897a773 100644
>> --- a/Documentation/admin-guide/mm/pagemap.rst
>> +++ b/Documentation/admin-guide/mm/pagemap.rst
>> @@ -91,9 +91,9 @@ Short descriptions to the page flags
>>     The page is being locked for exclusive access, e.g. by undergoing read/write
>>     IO.
>>  7 - SLAB
>> -   The page is managed by the SLAB/SLOB/SLUB/SLQB kernel memory allocator.
>> -   When compound page is used, SLUB/SLQB will only set this flag on the head
>> -   page; SLOB will not flag it at all.
>> +   The page is managed by the SLAB/SLUB kernel memory allocator.
>> +   When compound page is used, either will only set this flag on the head
>> +   page..
>>  10 - BUDDY
>>      A free memory block managed by the buddy system allocator.
>>      The buddy system organizes free memory in blocks of various orders.
>> diff --git a/fs/proc/page.c b/fs/proc/page.c
>> index 6249c347809a..1356aeffd8dc 100644
>> --- a/fs/proc/page.c
>> +++ b/fs/proc/page.c
>> @@ -125,7 +125,7 @@ u64 stable_page_flags(struct page *page)
>>  	/*
>>  	 * pseudo flags for the well known (anonymous) memory mapped pages
>>  	 *
>> -	 * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
>> +	 * Note that page->_mapcount is overloaded in SLAB/SLUB, so the
> 
> SLUB does not overload _mapcount.

True, I overlooked that, thanks.

>>  	 * simple test in page_mapped() is not enough.
>>  	 */
>>  	if (!PageSlab(page) && page_mapped(page))
>> @@ -166,8 +166,7 @@ u64 stable_page_flags(struct page *page)
>>  
>>  	/*
>>  	 * Caveats on high order pages: page->_refcount will only be set
>> -	 * -1 on the head page; SLUB/SLQB do the same for PG_slab;
>> -	 * SLOB won't set PG_slab at all on compound pages.
>> +	 * -1 on the head page; SLAB/SLUB do the same for PG_slab;
> 
> I think this comment could be just saying that PG_buddy is only set on
> head page, not saying
> 
> _refcount is set to -1 on head page (is it even correct?)

It's not, that scheme is outdated. So I'll have it mention PG_buddy as you
suggest, but PG_slab also needs special care as it's not set on tail pages.
But I noticed the compound_head() is unnecessary as that's covered by
PageSlab() which is defined as PF_NO_TAIL. So the sum of modifications to
this patch:

diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst
index bb4aa897a773..c8f380271cad 100644
--- a/Documentation/admin-guide/mm/pagemap.rst
+++ b/Documentation/admin-guide/mm/pagemap.rst
@@ -93,7 +93,7 @@ Short descriptions to the page flags
 7 - SLAB
    The page is managed by the SLAB/SLUB kernel memory allocator.
    When compound page is used, either will only set this flag on the head
-   page..
+   page.
 10 - BUDDY
     A free memory block managed by the buddy system allocator.
     The buddy system organizes free memory in blocks of various orders.
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 1356aeffd8dc..195b077c0fac 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -125,7 +125,7 @@ u64 stable_page_flags(struct page *page)
 	/*
 	 * pseudo flags for the well known (anonymous) memory mapped pages
 	 *
-	 * Note that page->_mapcount is overloaded in SLAB/SLUB, so the
+	 * Note that page->_mapcount is overloaded in SLAB, so the
 	 * simple test in page_mapped() is not enough.
 	 */
 	if (!PageSlab(page) && page_mapped(page))
@@ -165,8 +165,8 @@ u64 stable_page_flags(struct page *page)
 
 
 	/*
-	 * Caveats on high order pages: page->_refcount will only be set
-	 * -1 on the head page; SLAB/SLUB do the same for PG_slab;
+	 * Caveats on high order pages: PG_buddy and PG_slab will only be set
+	 * on the head page.
 	 */
 	if (PageBuddy(page))
 		u |= 1 << KPF_BUDDY;
@@ -184,7 +184,7 @@ u64 stable_page_flags(struct page *page)
 	u |= kpf_copy_bit(k, KPF_LOCKED,	PG_locked);
 
 	u |= kpf_copy_bit(k, KPF_SLAB,		PG_slab);
-	if (PageTail(page) && PageSlab(compound_head(page)))
+	if (PageTail(page) && PageSlab(page))
 		u |= 1 << KPF_SLAB;
 
 	u |= kpf_copy_bit(k, KPF_ERROR,		PG_error);
diff mbox series

Patch

diff --git a/Documentation/admin-guide/mm/pagemap.rst b/Documentation/admin-guide/mm/pagemap.rst
index b5f970dc91e7..bb4aa897a773 100644
--- a/Documentation/admin-guide/mm/pagemap.rst
+++ b/Documentation/admin-guide/mm/pagemap.rst
@@ -91,9 +91,9 @@  Short descriptions to the page flags
    The page is being locked for exclusive access, e.g. by undergoing read/write
    IO.
 7 - SLAB
-   The page is managed by the SLAB/SLOB/SLUB/SLQB kernel memory allocator.
-   When compound page is used, SLUB/SLQB will only set this flag on the head
-   page; SLOB will not flag it at all.
+   The page is managed by the SLAB/SLUB kernel memory allocator.
+   When compound page is used, either will only set this flag on the head
+   page..
 10 - BUDDY
     A free memory block managed by the buddy system allocator.
     The buddy system organizes free memory in blocks of various orders.
diff --git a/fs/proc/page.c b/fs/proc/page.c
index 6249c347809a..1356aeffd8dc 100644
--- a/fs/proc/page.c
+++ b/fs/proc/page.c
@@ -125,7 +125,7 @@  u64 stable_page_flags(struct page *page)
 	/*
 	 * pseudo flags for the well known (anonymous) memory mapped pages
 	 *
-	 * Note that page->_mapcount is overloaded in SLOB/SLUB/SLQB, so the
+	 * Note that page->_mapcount is overloaded in SLAB/SLUB, so the
 	 * simple test in page_mapped() is not enough.
 	 */
 	if (!PageSlab(page) && page_mapped(page))
@@ -166,8 +166,7 @@  u64 stable_page_flags(struct page *page)
 
 	/*
 	 * Caveats on high order pages: page->_refcount will only be set
-	 * -1 on the head page; SLUB/SLQB do the same for PG_slab;
-	 * SLOB won't set PG_slab at all on compound pages.
+	 * -1 on the head page; SLAB/SLUB do the same for PG_slab;
 	 */
 	if (PageBuddy(page))
 		u |= 1 << KPF_BUDDY;