linux-kernel - [PATCH 5/5] mm/hmm: WARN on illegal ->sync_cpu_device

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Date:   Wed, 14 Aug 2019 22:20:27 +0200
From:   Daniel Vetter <daniel.vetter@...ll.ch>
To:     LKML <linux-kernel@...r.kernel.org>
Cc:     linux-mm@...ck.org,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Intel Graphics Development <intel-gfx@...ts.freedesktop.org>,
        Daniel Vetter <daniel.vetter@...ll.ch>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Ralph Campbell <rcampbell@...dia.com>,
        John Hubbard <jhubbard@...dia.com>,
        Dan Williams <dan.j.williams@...el.com>,
        Dan Carpenter <dan.carpenter@...cle.com>,
        Matthew Wilcox <willy@...radead.org>,
        Arnd Bergmann <arnd@...db.de>,
        Balbir Singh <bsingharora@...il.com>,
        Ira Weiny <ira.weiny@...el.com>,
        Souptick Joarder <jrdr.linux@...il.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Jérôme Glisse <jglisse@...hat.com>,
        Daniel Vetter <daniel.vetter@...el.com>
Subject: [PATCH 5/5] mm/hmm: WARN on illegal ->sync_cpu_device_pagetables errors

Similar to the warning in the mmu notifer, warning if an hmm mirror
callback gets it's blocking vs. nonblocking handling wrong, or if it
fails with anything else than -EAGAIN.

Cc: Jason Gunthorpe <jgg@...pe.ca>
Cc: Ralph Campbell <rcampbell@...dia.com>
Cc: John Hubbard <jhubbard@...dia.com>
Cc: Dan Williams <dan.j.williams@...el.com>
Cc: Dan Carpenter <dan.carpenter@...cle.com>
Cc: Matthew Wilcox <willy@...radead.org>
Cc: Arnd Bergmann <arnd@...db.de>
Cc: Balbir Singh <bsingharora@...il.com>
Cc: Ira Weiny <ira.weiny@...el.com>
Cc: Souptick Joarder <jrdr.linux@...il.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>
Cc: "Jérôme Glisse" <jglisse@...hat.com>
Cc: linux-mm@...ck.org
Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
---
 mm/hmm.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/mm/hmm.c b/mm/hmm.c
index 16b6731a34db..52ac59384268 100644
--- a/mm/hmm.c
+++ b/mm/hmm.c
@@ -205,6 +205,9 @@ static int hmm_invalidate_range_start(struct mmu_notifier *mn,
 			ret = -EAGAIN;
 			break;
 		}
+		WARN(ret, "%pS callback failed with %d in %sblockable context\n",
+		     mirror->ops->sync_cpu_device_pagetables, ret,
+		     update.blockable ? "" : "non-");
 	}
 	up_read(&hmm->mirrors_sem);
 
-- 
2.22.0