linux-kernel - [PATCH] mm, notifier: Fix early return case for new lockdep annotations

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Message-Id: <20190906174730.22462-1-daniel.vetter@ffwll.ch>
Date:   Fri,  6 Sep 2019 19:47:30 +0200
From:   Daniel Vetter <daniel.vetter@...ll.ch>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     DRI Development <dri-devel@...ts.freedesktop.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        syzbot+aaedc50d99a03250fe1f@...kaller.appspotmail.com,
        Jason Gunthorpe <jgg@...lanox.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jérôme Glisse <jglisse@...hat.com>,
        Ralph Campbell <rcampbell@...dia.com>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Ira Weiny <ira.weiny@...el.com>,
        Michal Hocko <mhocko@...e.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        linux-mm@...ck.org
Subject: [PATCH] mm, notifier: Fix early return case for new lockdep annotations

I missed that when extending the lockdep annotations to the
nonblocking case.

I missed this while testing since in the i915 mmu notifiers is hitting
a nice lockdep splat already before the point of going into oom killer
mode :-/

Reported-by: syzbot+aaedc50d99a03250fe1f@...kaller.appspotmail.com
Fixes: d2b219ed03d4 ("mm/mmu_notifiers: add a lockdep map for invalidate_range_start/end")
Cc: Jason Gunthorpe <jgg@...lanox.com>
Cc: Daniel Vetter <daniel.vetter@...el.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: "Jérôme Glisse" <jglisse@...hat.com>
Cc: Ralph Campbell <rcampbell@...dia.com>
Cc: Jason Gunthorpe <jgg@...pe.ca>
Cc: Ira Weiny <ira.weiny@...el.com>
Cc: Michal Hocko <mhocko@...e.com>
Cc: Daniel Vetter <daniel.vetter@...ll.ch>
Cc: Sean Christopherson <sean.j.christopherson@...el.com>
Cc: Jean-Philippe Brucker <jean-philippe@...aro.org>
Cc: linux-mm@...ck.org
Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
---
 include/linux/mmu_notifier.h | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/include/linux/mmu_notifier.h b/include/linux/mmu_notifier.h
index 5a03417e5bf7..4edd98b06834 100644
--- a/include/linux/mmu_notifier.h
+++ b/include/linux/mmu_notifier.h
@@ -356,13 +356,14 @@ mmu_notifier_invalidate_range_start(struct mmu_notifier_range *range)
 static inline int
 mmu_notifier_invalidate_range_start_nonblock(struct mmu_notifier_range *range)
 {
+	int ret = 0;
 	lock_map_acquire(&__mmu_notifier_invalidate_range_start_map);
 	if (mm_has_notifiers(range->mm)) {
 		range->flags &= ~MMU_NOTIFIER_RANGE_BLOCKABLE;
-		return __mmu_notifier_invalidate_range_start(range);
+		ret = __mmu_notifier_invalidate_range_start(range);
 	}
 	lock_map_release(&__mmu_notifier_invalidate_range_start_map);
-	return 0;
+	return ret;
 }
 
 static inline void
-- 
2.23.0