Commit f87854c9 authored by Lorenzo Stoakes (Oracle)'s avatar Lorenzo Stoakes (Oracle) Committed by Andrew Morton
Browse files

mm/huge_memory: separate out the folio part of zap_huge_pmd() 

Place the part of the logic that manipulates counters and possibly updates
the accessed bit of the folio into its own function to make zap_huge_pmd()
more readable.

Also rename flush_needed to is_present as we only require a flush for
present entries.

Additionally add comments as to why we're doing what we're doing with
respect to softleaf entries.

This also lays the ground for further refactoring.

Link: https://lkml.kernel.org/r/6c4db67952f5529da4db102a6149b9050b5dda4e.1774029655.git.ljs@kernel.org


Signed-off-by: default avatarLorenzo Stoakes (Oracle) <ljs@kernel.org>
Reviewed-by: default avatarBaolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: default avatarSuren Baghdasaryan <surenb@google.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 1c6b7ff6

mm/huge_memory.c

+35 −26
Original line number Diff line number Diff line
@@ -2402,6 +2402,37 @@ static inline void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd) 
	mm_dec_nr_ptes(mm);

}



static void zap_huge_pmd_folio(struct mm_struct *mm, struct vm_area_struct *vma,

		pmd_t pmdval, struct folio *folio, bool is_present,

		bool *has_deposit)

{

	const bool is_device_private = folio_is_device_private(folio);



	/* Present and device private folios are rmappable. */

	if (is_present || is_device_private)

		folio_remove_rmap_pmd(folio, &folio->page, vma);



	if (folio_test_anon(folio)) {

		*has_deposit = true;

		add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR);

	} else {

		add_mm_counter(mm, mm_counter_file(folio),

			       -HPAGE_PMD_NR);



		/*

		 * Use flush_needed to indicate whether the PMD entry

		 * is present, instead of checking pmd_present() again.

		 */

		if (is_present && pmd_young(pmdval) &&

		    likely(vma_has_recency(vma)))

			folio_mark_accessed(folio);

	}



	/* Device private folios are pinned. */

	if (is_device_private)

		folio_put(folio);

}



/**

 * zap_huge_pmd - Zap a huge THP which is of PMD size.

 * @tlb: The MMU gather TLB state associated with the operation.
@@ -2417,7 +2448,7 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 
	bool has_deposit = arch_needs_pgtable_deposit();

	struct mm_struct *mm = tlb->mm;

	struct folio *folio = NULL;

	bool flush_needed = false;

	bool is_present = false;

	spinlock_t *ptl;

	pmd_t orig_pmd;
@@ -2446,14 +2477,11 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 


	if (pmd_present(orig_pmd)) {

		folio = pmd_folio(orig_pmd);



		flush_needed = true;

		folio_remove_rmap_pmd(folio, &folio->page, vma);

		is_present = true;

	} else if (pmd_is_valid_softleaf(orig_pmd)) {

		const softleaf_t entry = softleaf_from_pmd(orig_pmd);



		folio = softleaf_to_folio(entry);



		if (!thp_migration_supported())

			WARN_ONCE(1, "Non present huge pmd without pmd migration enabled!");

	} else {
@@ -2461,33 +2489,14 @@ bool zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma, 
		goto out;

	}



	if (folio_test_anon(folio)) {

		has_deposit = true;

		add_mm_counter(mm, MM_ANONPAGES, -HPAGE_PMD_NR);

	} else {

		add_mm_counter(mm, mm_counter_file(folio),

			       -HPAGE_PMD_NR);



		/*

		 * Use flush_needed to indicate whether the PMD entry

		 * is present, instead of checking pmd_present() again.

		 */

		if (flush_needed && pmd_young(orig_pmd) &&

		    likely(vma_has_recency(vma)))

			folio_mark_accessed(folio);

	}



	if (folio_is_device_private(folio)) {

		folio_remove_rmap_pmd(folio, &folio->page, vma);

		folio_put(folio);

	}

	zap_huge_pmd_folio(mm, vma, orig_pmd, folio, is_present, &has_deposit);



out:

	if (has_deposit)

		zap_deposited_table(mm, pmd);



	spin_unlock(ptl);

	if (flush_needed)

	if (is_present)

		tlb_remove_page_size(tlb, &folio->page, HPAGE_PMD_SIZE);

	return true;

}