linux-kernel - Re: [PATCH v3 3/3] fb_defio: do not use deprecated page->mapping, index fields

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Message-ID: <d4018405-2762-4385-a816-e54cc23839ac@lucifer.local>
Date: Sun, 9 Feb 2025 06:36:02 +0000
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Jaya Kumar <jayakumar.lkml@...il.com>, Simona Vetter <simona@...ll.ch>,
        Helge Deller <deller@....de>, linux-fbdev@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Matthew Wilcox <willy@...radead.org>,
        David Hildenbrand <david@...hat.com>,
        Kajtar Zsolt <soci@....rulez.org>, Maira Canal <mcanal@...lia.com>,
        Simona Vetter <simona.vetter@...ll.ch>,
        Thomas Zimmermann <tzimmermann@...e.de>
Subject: Re: [PATCH v3 3/3] fb_defio: do not use deprecated page->mapping,
 index fields

Andrew - apologies for this, I managed to miss some unusued variable warnings in
this nommu workaround, once you take the v3 could you apply this trivial
fix-patch on top to resolve that?

I tested this locally to confirm it resolves the problem. Thanks!

----8<----
>From f428a950a5a932c0e4404a89f2a34b0683728016 Mon Sep 17 00:00:00 2001
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
Date: Sun, 9 Feb 2025 06:29:25 +0000
Subject: [PATCH] mm: fixup unused variable warnings

Unfortunately fb_defio being enabled by nommu devices seems enormously
ingrained in the kernel to the point that it's not feasible to address that
in this series, so we use an ifdef to workaround.

However this workaround unfortunately missed some unused variables -
correct this.

This has been tested locally with W=1 and confirmed to resolve the issue.

Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
---
 drivers/video/fbdev/core/fb_defio.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/core/fb_defio.c b/drivers/video/fbdev/core/fb_defio.c
index acf7bc7ac45f..4fc93f253e06 100644
--- a/drivers/video/fbdev/core/fb_defio.c
+++ b/drivers/video/fbdev/core/fb_defio.c
@@ -265,15 +265,15 @@ static void fb_deferred_io_work(struct work_struct *work)

 	/* here we wrprotect the page's mappings, then do all deferred IO. */
 	mutex_lock(&fbdefio->lock);
+#ifdef CONFIG_MMU
 	list_for_each_entry(pageref, &fbdefio->pagereflist, list) {
 		struct page *page = pageref->page;
 		pgoff_t pgoff = pageref->offset >> PAGE_SHIFT;

-#ifdef CONFIG_MMU
 		mapping_wrprotect_range(fbdefio->mapping, pgoff,
 					page_to_pfn(page), 1);
-#endif
 	}
+#endif

 	/* driver's callback with pagereflist */
 	fbdefio->deferred_io(info, &fbdefio->pagereflist);
--
2.48.1