linux-kernel - [PATCH v3 6/9] mm: make zap_pte_range() handle full within-PMD range

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Message-Id: <3aaf6c2338372866b85cea78140f5ea497ccc33d.1731566457.git.zhengqi.arch@bytedance.com>
Date: Thu, 14 Nov 2024 14:59:57 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: david@...hat.com,
	jannh@...gle.com,
	hughd@...gle.com,
	willy@...radead.org,
	muchun.song@...ux.dev,
	vbabka@...nel.org,
	akpm@...ux-foundation.org,
	peterx@...hat.com
Cc: mgorman@...e.de,
	catalin.marinas@....com,
	will@...nel.org,
	dave.hansen@...ux.intel.com,
	luto@...nel.org,
	peterz@...radead.org,
	x86@...nel.org,
	lorenzo.stoakes@...cle.com,
	linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	zokeefe@...gle.com,
	rientjes@...gle.com,
	Qi Zheng <zhengqi.arch@...edance.com>
Subject: [PATCH v3 6/9] mm: make zap_pte_range() handle full within-PMD range

In preparation for reclaiming empty PTE pages, this commit first makes
zap_pte_range() to handle the full within-PMD range, so that we can more
easily detect and free PTE pages in this function in subsequent commits.

Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
Reviewed-by: Jann Horn <jannh@...gle.com>
---
 mm/memory.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/memory.c b/mm/memory.c
index bf5ac8e0b4656..8b3348ff374ff 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1711,6 +1711,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 	pte_t *pte;
 	int nr;
 
+retry:
 	tlb_change_page_size(tlb, PAGE_SIZE);
 	init_rss_vec(rss);
 	start_pte = pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
@@ -1758,6 +1759,13 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 	if (force_flush)
 		tlb_flush_mmu(tlb);
 
+	if (addr != end) {
+		cond_resched();
+		force_flush = false;
+		force_break = false;
+		goto retry;
+	}
+
 	return addr;
 }
 
-- 
2.20.1