linux-kernel - [PATCH] mm/thp: fix call to mmu_notifier in set_pmd_migration

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Message-Id: <20181012160953.5841-1-jglisse@redhat.com>
Date:   Fri, 12 Oct 2018 12:09:53 -0400
From:   jglisse@...hat.com
To:     linux-mm@...ck.org
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        linux-kernel@...r.kernel.org,
        Jérôme Glisse <jglisse@...hat.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Zi Yan <zi.yan@...rutgers.edu>,
        "Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
        "H. Peter Anvin" <hpa@...or.com>,
        Anshuman Khandual <khandual@...ux.vnet.ibm.com>,
        Dave Hansen <dave.hansen@...el.com>,
        David Nellans <dnellans@...dia.com>,
        Ingo Molnar <mingo@...e.hu>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Minchan Kim <minchan@...nel.org>,
        Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vlastimil Babka <vbabka@...e.cz>,
        Michal Hocko <mhocko@...nel.org>,
        Andrea Arcangeli <aarcange@...hat.com>
Subject: [PATCH] mm/thp: fix call to mmu_notifier in set_pmd_migration_entry()

From: Jérôme Glisse <jglisse@...hat.com>

Inside set_pmd_migration_entry() we are holding page table locks and
thus we can not sleep so we can not call invalidate_range_start/end()

So remove call to mmu_notifier_invalidate_range_start/end() and add
call to mmu_notifier_invalidate_range(). Note that we are already
calling mmu_notifier_invalidate_range_start/end() inside the function
calling set_pmd_migration_entry() (see try_to_unmap_one()).

Signed-off-by: Jérôme Glisse <jglisse@...hat.com>
Reported-by: Andrea Arcangeli <aarcange@...hat.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: Zi Yan <zi.yan@...rutgers.edu>
Cc: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Anshuman Khandual <khandual@...ux.vnet.ibm.com>
Cc: Dave Hansen <dave.hansen@...el.com>
Cc: David Nellans <dnellans@...dia.com>
Cc: Ingo Molnar <mingo@...e.hu>
Cc: Mel Gorman <mgorman@...hsingularity.net>
Cc: Minchan Kim <minchan@...nel.org>
Cc: Naoya Horiguchi <n-horiguchi@...jp.nec.com>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Vlastimil Babka <vbabka@...e.cz>
Cc: Michal Hocko <mhocko@...nel.org>
Cc: Andrea Arcangeli <aarcange@...hat.com>
---
 mm/huge_memory.c | 7 +------
 1 file changed, 1 insertion(+), 6 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 533f9b00147d..93cb80fe12cb 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -2885,9 +2885,6 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
 	if (!(pvmw->pmd && !pvmw->pte))
 		return;
 
-	mmu_notifier_invalidate_range_start(mm, address,
-			address + HPAGE_PMD_SIZE);
-
 	flush_cache_range(vma, address, address + HPAGE_PMD_SIZE);
 	pmdval = *pvmw->pmd;
 	pmdp_invalidate(vma, address, pvmw->pmd);
@@ -2898,11 +2895,9 @@ void set_pmd_migration_entry(struct page_vma_mapped_walk *pvmw,
 	if (pmd_soft_dirty(pmdval))
 		pmdswp = pmd_swp_mksoft_dirty(pmdswp);
 	set_pmd_at(mm, address, pvmw->pmd, pmdswp);
+	mmu_notifier_invalidate_range(mm, address, address + HPAGE_PMD_SIZE);
 	page_remove_rmap(page, true);
 	put_page(page);
-
-	mmu_notifier_invalidate_range_end(mm, address,
-			address + HPAGE_PMD_SIZE);
 }
 
 void remove_migration_pmd(struct page_vma_mapped_walk *pvmw, struct page *new)
-- 
2.17.2