linux-kernel - [PATCH v1 2/7] mm: make zap_pte_range() handle full within-PMD range

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Message-Id: <cd03a570f23e67016d23c3aa27f5931715570416.1729157502.git.zhengqi.arch@bytedance.com>
Date: Thu, 17 Oct 2024 17:47:21 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: david@...hat.com,
	hughd@...gle.com,
	willy@...radead.org,
	mgorman@...e.de,
	muchun.song@...ux.dev,
	vbabka@...nel.org,
	akpm@...ux-foundation.org,
	zokeefe@...gle.com,
	rientjes@...gle.com,
	jannh@...gle.com,
	peterx@...hat.com
Cc: linux-mm@...ck.org,
	linux-kernel@...r.kernel.org,
	x86@...nel.org,
	Qi Zheng <zhengqi.arch@...edance.com>
Subject: [PATCH v1 2/7] 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>
---
 mm/memory.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/mm/memory.c b/mm/memory.c
index caa6ed0a7fe5b..fd57c0f49fce2 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1602,6 +1602,7 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 	swp_entry_t entry;
 	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);
@@ -1706,6 +1707,11 @@ static unsigned long zap_pte_range(struct mmu_gather *tlb,
 	if (force_flush)
 		tlb_flush_mmu(tlb);
 
+	if (addr != end) {
+		cond_resched();
+		goto retry;
+	}
+
 	return addr;
 }
 
@@ -1744,8 +1750,6 @@ static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
 			continue;
 		}
 		addr = zap_pte_range(tlb, vma, pmd, addr, next, details);
-		if (addr != next)
-			pmd--;
 	} while (pmd++, cond_resched(), addr != end);
 
 	return addr;
-- 
2.20.1