mm: introduce page reference manipulation functions (fe896d18) · Commits · 戴 / test

The success of CMA allocation largely depends on the success of migration and key factor of it is page reference count. Until now, page reference is manipulated by direct calling atomic functions so we cannot follow up who and where manipulate it. Then, it is hard to find actual reason of CMA allocation failure. CMA allocation should be guaranteed to succeed so finding offending place is really important. In this patch, call sites where page reference is manipulated are converted to introduced wrapper function. This is preparation step to add tracepoint to each page reference manipulation function. With this facility, we can easily find reason of CMA allocation failure. There is no functional change in this patch. In addition, this patch also converts reference read sites. It will help a second step that renames page._count to something else and prevents later attempt to direct access to it (Suggested by Andrew). Signed-off-by:

Joonsoo Kim <iamjoonsoo.kim@lge.com> Acked-by:

Michal Nazarewicz <mina86@mina86.com> Acked-by:

Vlastimil Babka <vbabka@suse.cz> Cc: Minchan Kim <minchan@kernel.org> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com> Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> Cc: Steven Rostedt <rostedt@goodmis.org> Signed-off-by:

Andrew Morton <akpm@linux-foundation.org> Signed-off-by:

Linus Torvalds <torvalds@linux-foundation.org>

arch/mips/mm/gup.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -64,7 +64,7 @@ static inline void get_head_page_multiple(struct page *page, int nr)
		{
		VM_BUG_ON(page != compound_head(page));
		VM_BUG_ON(page_count(page) == 0);
		atomic_add(nr, &page->_count);
		page_ref_add(page, nr);
		SetPageReferenced(page);
		}

arch/powerpc/mm/mmu_context_hash64.c

+1 −2

Original line number	Diff line number	Diff line
		@@ -118,8 +118,7 @@ static void destroy_pagetable_page(struct mm_struct *mm)
		/* drop all the pending references */
		count = ((unsigned long)pte_frag & ~PAGE_MASK) >> PTE_FRAG_SIZE_SHIFT;
		/* We allow PTE_FRAG_NR fragments from a PTE page */
		count = atomic_sub_return(PTE_FRAG_NR - count, &page->_count);
		if (!count) {
		if (page_ref_sub_and_test(page, PTE_FRAG_NR - count)) {
		pgtable_page_dtor(page);
		free_hot_cold_page(page, 0);
		}

arch/powerpc/mm/pgtable_64.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -403,7 +403,7 @@ static pte_t __alloc_for_cache(struct mm_struct mm, int kernel)
		* count.
		*/
		if (likely(!mm->context.pte_frag)) {
		atomic_set(&page->_count, PTE_FRAG_NR);
		set_page_count(page, PTE_FRAG_NR);
		mm->context.pte_frag = ret + PTE_FRAG_SIZE;
		}
		spin_unlock(&mm->page_table_lock);

arch/powerpc/platforms/512x/mpc512x_shared.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -188,7 +188,7 @@ static struct fsl_diu_shared_fb __attribute__ ((__aligned__(8))) diu_shared_fb;
		static inline void mpc512x_free_bootmem(struct page *page)
		{
		BUG_ON(PageTail(page));
		BUG_ON(atomic_read(&page->_count) > 1);
		BUG_ON(page_ref_count(page) > 1);
		free_reserved_page(page);
		}

arch/x86/mm/gup.c

+1 −1

Original line number	Diff line number	Diff line
		@@ -131,7 +131,7 @@ static inline void get_head_page_multiple(struct page *page, int nr)
		{
		VM_BUG_ON_PAGE(page != compound_head(page), page);
		VM_BUG_ON_PAGE(page_count(page) == 0, page);
		atomic_add(nr, &page->_count);
		page_ref_add(page, nr);
		SetPageReferenced(page);
		}

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