linux-kernel - [PATCH v2 9/9] x86/clear_huge_page: make clear_contig

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Date:   Wed, 30 Aug 2023 11:49:58 -0700
From:   Ankur Arora <ankur.a.arora@...cle.com>
To:     linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org
Cc:     akpm@...ux-foundation.org, luto@...nel.org, bp@...en8.de,
        dave.hansen@...ux.intel.com, hpa@...or.com, mingo@...hat.com,
        juri.lelli@...hat.com, vincent.guittot@...aro.org,
        willy@...radead.org, mgorman@...e.de, peterz@...radead.org,
        rostedt@...dmis.org, tglx@...utronix.de, jon.grimm@....com,
        bharata@....com, raghavendra.kt@....com,
        boris.ostrovsky@...cle.com, konrad.wilk@...cle.com,
        Ankur Arora <ankur.a.arora@...cle.com>
Subject: [PATCH v2 9/9] x86/clear_huge_page: make clear_contig_region() preemptible

clear_contig_region() can be used for clearing  regions as large as a
gigantic page. Allow preemption in irqentry_exit to make sure we don't
hold on to the CPU for an arbitrarily long period.

Signed-off-by: Ankur Arora <ankur.a.arora@...cle.com>
---
 arch/x86/mm/hugetlbpage.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/arch/x86/mm/hugetlbpage.c b/arch/x86/mm/hugetlbpage.c
index 0b9f7a6dad93..55d1d15ea618 100644
--- a/arch/x86/mm/hugetlbpage.c
+++ b/arch/x86/mm/hugetlbpage.c
@@ -152,7 +152,12 @@ hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
 #ifndef CONFIG_HIGHMEM
 static void clear_contig_region(struct page *page, unsigned int npages)
 {
+	/*
+	 * We might be clearing a large region. Allow rescheduling.
+	 */
+	allow_resched();
 	clear_pages(page_address(page), npages);
+	disallow_resched();
 }
 
 /*
-- 
2.31.1