linux-kernel - [PATCH v2 24/35] mm: write lock mmu_notifier

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Date:   Fri, 28 Jan 2022 05:09:55 -0800
From:   Michel Lespinasse <michel@...pinasse.org>
To:     Linux-MM <linux-mm@...ck.org>, linux-kernel@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     kernel-team@...com, Laurent Dufour <ldufour@...ux.ibm.com>,
        Jerome Glisse <jglisse@...gle.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Michal Hocko <mhocko@...e.com>,
        Vlastimil Babka <vbabka@...e.cz>,
        Davidlohr Bueso <dave@...olabs.net>,
        Matthew Wilcox <willy@...radead.org>,
        Liam Howlett <liam.howlett@...cle.com>,
        Rik van Riel <riel@...riel.com>,
        Paul McKenney <paulmck@...nel.org>,
        Song Liu <songliubraving@...com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Minchan Kim <minchan@...gle.com>,
        Joel Fernandes <joelaf@...gle.com>,
        David Rientjes <rientjes@...gle.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Andy Lutomirski <luto@...nel.org>,
        Michel Lespinasse <michel@...pinasse.org>
Subject: [PATCH v2 24/35] mm: write lock mmu_notifier_lock when registering mmu notifiers

Change mm_take_all_locks to also take the mmu_notifier_lock.
Note that mm_take_all_locks is called from mmu_notifier_register() only.

Signed-off-by: Michel Lespinasse <michel@...pinasse.org>
---
 mm/mmap.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/mm/mmap.c b/mm/mmap.c
index b09a2c875507..a67c3600d995 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -3592,6 +3592,10 @@ int mm_take_all_locks(struct mm_struct *mm)
 
 	mutex_lock(&mm_all_locks_mutex);
 
+#if defined(CONFIG_MMU_NOTIFIER) && defined(CONFIG_SPECULATIVE_PAGE_FAULT)
+	percpu_down_write(mm->mmu_notifier_lock);
+#endif
+
 	for (vma = mm->mmap; vma; vma = vma->vm_next) {
 		if (signal_pending(current))
 			goto out_unlock;
@@ -3679,6 +3683,10 @@ void mm_drop_all_locks(struct mm_struct *mm)
 			vm_unlock_mapping(vma->vm_file->f_mapping);
 	}
 
+#if defined(CONFIG_MMU_NOTIFIER) && defined(CONFIG_SPECULATIVE_PAGE_FAULT)
+	percpu_up_write(mm->mmu_notifier_lock);
+#endif
+
 	mutex_unlock(&mm_all_locks_mutex);
 }
 
-- 
2.20.1