linux-kernel - [PATCH 4/4] mm: Add PGREUSE counter

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Message-Id: <20200821234958.7896-5-peterx@redhat.com>
Date:   Fri, 21 Aug 2020 19:49:58 -0400
From:   Peter Xu <peterx@...hat.com>
To:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc:     "Maya B . Gokhale" <gokhale2@...l.gov>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Yang Shi <yang.shi@...ux.alibaba.com>,
        Marty Mcfadden <mcfadden8@...l.gov>, peterx@...hat.com,
        Kirill Shutemov <kirill@...temov.name>,
        Oleg Nesterov <oleg@...hat.com>, Jann Horn <jannh@...gle.com>,
        Jan Kara <jack@...e.cz>, Kirill Tkhai <ktkhai@...tuozzo.com>,
        Andrea Arcangeli <aarcange@...hat.com>,
        Christoph Hellwig <hch@....de>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: [PATCH 4/4] mm: Add PGREUSE counter

This accounts for wp_page_reuse() case, where we reused a page for COW.

Signed-off-by: Peter Xu <peterx@...hat.com>
---
 include/linux/vm_event_item.h | 1 +
 mm/memory.c                   | 1 +
 mm/vmstat.c                   | 1 +
 3 files changed, 3 insertions(+)

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 2e6ca53b9bbd..18e75974d4e3 100644
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -30,6 +30,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
 		PGFAULT, PGMAJFAULT,
 		PGLAZYFREED,
 		PGREFILL,
+		PGREUSE,
 		PGSTEAL_KSWAPD,
 		PGSTEAL_DIRECT,
 		PGSCAN_KSWAPD,
diff --git a/mm/memory.c b/mm/memory.c
index cb9006189d22..148eafb8cbb1 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2622,6 +2622,7 @@ static inline void wp_page_reuse(struct vm_fault *vmf)
 	if (ptep_set_access_flags(vma, vmf->address, vmf->pte, entry, 1))
 		update_mmu_cache(vma, vmf->address, vmf->pte);
 	pte_unmap_unlock(vmf->pte, vmf->ptl);
+	count_vm_event(PGREUSE);
 }
 
 /*
diff --git a/mm/vmstat.c b/mm/vmstat.c
index e670f910cd2f..4f7b4ee6aa12 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -1241,6 +1241,7 @@ const char * const vmstat_text[] = {
 	"pglazyfreed",
 
 	"pgrefill",
+	"pgreuse",
 	"pgsteal_kswapd",
 	"pgsteal_direct",
 	"pgscan_kswapd",
-- 
2.26.2