Commit 4dc7d373 authored by Matthew Wilcox (Oracle)'s avatar Matthew Wilcox (Oracle) Committed by Andrew Morton
Browse files

remove references to page->flags in documentation 

Mostly rewording, but remove entirely the copy of page_fixed_fake_head()
in the documentation; we can refer people to the actual source if
necessary.

Link: https://lkml.kernel.org/r/20240326171045.410737-10-willy@infradead.org


Signed-off-by: default avatarMatthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 5e0debe0

Documentation/admin-guide/cgroup-v1/memory.rst

+2 −2
Original line number Diff line number Diff line
@@ -300,14 +300,14 @@ When oom event notifier is registered, event will be delivered. 


Lock order is as follows::



  Page lock (PG_locked bit of page->flags)

  folio_lock

    mm->page_table_lock or split pte_lock

      folio_memcg_lock (memcg->move_lock)

        mapping->i_pages lock

          lruvec->lru_lock.



Per-node-per-memcgroup LRU (cgroup's private LRU) is guarded by

lruvec->lru_lock; PG_lru bit of page->flags is cleared before

lruvec->lru_lock; the folio LRU flag is cleared before

isolating a page from its LRU under lruvec->lru_lock.



.. _cgroup-v1-memory-kernel-extension:

Documentation/mm/vmemmap_dedup.rst

+1 −21
Original line number Diff line number Diff line
@@ -180,27 +180,7 @@ this correctly. There is only **one** head ``struct page``, the tail 
``struct page`` with ``PG_head`` are fake head ``struct page``.  We need an

approach to distinguish between those two different types of ``struct page`` so

that ``compound_head()`` can return the real head ``struct page`` when the

parameter is the tail ``struct page`` but with ``PG_head``. The following code

snippet describes how to distinguish between real and fake head ``struct page``.



.. code-block:: c



	if (test_bit(PG_head, &page->flags)) {

		unsigned long head = READ_ONCE(page[1].compound_head);



		if (head & 1) {

			if (head == (unsigned long)page + 1)

				/* head struct page */

			else

				/* tail struct page */

		} else {

			/* head struct page */

		}

	}



We can safely access the field of the **page[1]** with ``PG_head`` because the

page is a compound page composed with at least two contiguous pages.

The implementation refers to ``page_fixed_fake_head()``.

parameter is the tail ``struct page`` but with ``PG_head``.



Device DAX

==========

Documentation/translations/zh_CN/core-api/cachetlb.rst

+1 −1
Original line number Diff line number Diff line
@@ -260,7 +260,7 @@ HyperSparc cpu就是这样一个具有这种属性的cpu。 
	如果D-cache别名不是一个问题，这个程序可以简单地定义为该架构上

	的nop。



	在page->flags (PG_arch_1)中有一个位是“架构私有”。内核保证，

	在folio->flags (PG_arch_1)中有一个位是“架构私有”。内核保证，

	对于分页缓存的页面，当这样的页面第一次进入分页缓存时，它将清除

	这个位。

mm/migrate.c

+1 −1
Original line number Diff line number Diff line
@@ -113,7 +113,7 @@ bool isolate_movable_page(struct page *page, isolate_mode_t mode) 
	if (!mops->isolate_page(&folio->page, mode))

		goto out_no_isolated;



	/* Driver shouldn't use PG_isolated bit of page->flags */

	/* Driver shouldn't use the isolated flag */

	WARN_ON_ONCE(folio_test_isolated(folio));

	folio_set_isolated(folio);

	folio_unlock(folio);

mm/rmap.c

+2 −2
Original line number Diff line number Diff line
@@ -23,7 +23,7 @@ 
 * inode->i_rwsem	(while writing or truncating, not reading or faulting)

 *   mm->mmap_lock

 *     mapping->invalidate_lock (in filemap_fault)

 *       page->flags PG_locked (lock_page)

 *       folio_lock

 *         hugetlbfs_i_mmap_rwsem_key (in huge_pmd_share, see hugetlbfs below)

 *           vma_start_write

 *             mapping->i_mmap_rwsem
@@ -50,7 +50,7 @@ 
 *   hugetlb_fault_mutex (hugetlbfs specific page fault mutex)

 *     vma_lock (hugetlb specific lock for pmd_sharing)

 *       mapping->i_mmap_rwsem (also used for hugetlb pmd sharing)

 *         page->flags PG_locked (lock_page)

 *         folio_lock

 */



#include <linux/mm.h>