Commit 736b378b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'slab-for-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab 

Pull slab updates from Vlastimil Babka:
 "The main change is naturally the SLOB removal. Since its deprecation
  in 6.2 I've seen no complaints so hopefully SLUB_(TINY) works well for
  everyone and we can proceed.

  Besides the code cleanup, the main immediate benefit will be allowing
  kfree() family of function to work on kmem_cache_alloc() objects,
  which was incompatible with SLOB. This includes kfree_rcu() which had
  no kmem_cache_free_rcu() counterpart yet and now it shouldn't be
  necessary anymore.

  Besides that, there are several small code and comment improvements
  from Thomas, Thorsten and Vernon"

* tag 'slab-for-6.4' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
  mm/slab: document kfree() as allowed for kmem_cache_alloc() objects
  mm/slob: remove slob.c
  mm/slab: remove CONFIG_SLOB code from slab common code
  mm, pagemap: remove SLOB and SLQB from comments and documentation
  mm, page_flags: remove PG_slob_free
  mm/slob: remove CONFIG_SLOB
  mm/slub: fix help comment of SLUB_DEBUG
  mm: slub: make kobj_type structure constant
  slab: Adjust comment after refactoring of gfp.h
parents 11704531 ed4cdfbe

Documentation/admin-guide/mm/pagemap.rst

+3 −3
Original line number Diff line number Diff line
@@ -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.

Documentation/core-api/memory-allocation.rst

+13 −4
Original line number Diff line number Diff line
@@ -170,7 +170,16 @@ should be used if a part of the cache might be copied to the userspace. 
After the cache is created kmem_cache_alloc() and its convenience

wrappers can allocate memory from that cache.



When the allocated memory is no longer needed it must be freed. You can

use kvfree() for the memory allocated with `kmalloc`, `vmalloc` and

`kvmalloc`. The slab caches should be freed with kmem_cache_free(). And

don't forget to destroy the cache with kmem_cache_destroy().
 
When the allocated memory is no longer needed it must be freed.



Objects allocated by `kmalloc` can be freed by `kfree` or `kvfree`. Objects

allocated by `kmem_cache_alloc` can be freed with `kmem_cache_free`, `kfree`

or `kvfree`, where the latter two might be more convenient thanks to not

needing the kmem_cache pointer.



The same rules apply to _bulk and _rcu flavors of freeing functions.



Memory allocated by `vmalloc` can be freed with `vfree` or `kvfree`.

Memory allocated by `kvmalloc` can be freed with `kvfree`.

Caches created by `kmem_cache_create` should be freed with

`kmem_cache_destroy` only after freeing all the allocated objects first.

fs/proc/page.c

+4 −5
Original line number Diff line number Diff line
@@ -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, so the

	 * simple test in page_mapped() is not enough.

	 */

	if (!PageSlab(page) && page_mapped(page))
@@ -165,9 +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; SLUB/SLQB do the same for PG_slab;

	 * SLOB won't set PG_slab at all on compound pages.

	 * 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;
@@ -185,7 +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);

include/linux/page-flags.h

+0 −4
Original line number Diff line number Diff line
@@ -174,9 +174,6 @@ enum pageflags { 
	/* Remapped by swiotlb-xen. */

	PG_xen_remapped = PG_owner_priv_1,



	/* SLOB */

	PG_slob_free = PG_private,



#ifdef CONFIG_MEMORY_FAILURE

	/*

	 * Compound pages. Stored in first tail page's flags.
@@ -483,7 +480,6 @@ PAGEFLAG(Active, active, PF_HEAD) __CLEARPAGEFLAG(Active, active, PF_HEAD) 
PAGEFLAG(Workingset, workingset, PF_HEAD)

	TESTCLEARFLAG(Workingset, workingset, PF_HEAD)

__PAGEFLAG(Slab, slab, PF_NO_TAIL)

__PAGEFLAG(SlobFree, slob_free, PF_NO_TAIL)

PAGEFLAG(Checked, checked, PF_NO_COMPOUND)	   /* Used by some filesystems */



/* Xen */

include/linux/rcupdate.h

+4 −2
Original line number Diff line number Diff line
@@ -976,8 +976,10 @@ static inline notrace void rcu_read_unlock_sched_notrace(void) 
 * either fall back to use of call_rcu() or rearrange the structure to

 * position the rcu_head structure into the first 4096 bytes.

 *

 * Note that the allowable offset might decrease in the future, for example,

 * to allow something like kmem_cache_free_rcu().

 * The object to be freed can be allocated either by kmalloc() or

 * kmem_cache_alloc().

 *

 * Note that the allowable offset might decrease in the future.

 *

 * The BUILD_BUG_ON check must not involve any function calls, hence the

 * checks are done in macros here.