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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uMUT1-00000002DcX-44uI; Tue, 03 Jun 2025 16:26:24 +0000 Date: Tue, 3 Jun 2025 17:26:23 +0100 From: Matthew Wilcox To: Steven Rostedt Cc: Hugh Dickins , LKML , linux-mm@kvack.org, Andrew Morton , Linus Torvalds Subject: Re: [PATCH] mm: Fix compile error when CONFIG_SHMEM is not set Message-ID: References: <20250602170500.48713a2b@gandalf.local.home> <20250602171458.7ceabb1c@gandalf.local.home> <20250603102959.20c85adb@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250603102959.20c85adb@gandalf.local.home> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 119FC4000A X-Stat-Signature: ygwmock1w6b7cow7bmt8g99d8c7t3zki X-Rspam-User: X-HE-Tag: 1748967986-422292 X-HE-Meta: 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 KJtnCD39 kwYfMH8pk436p9NDWbJ9rS/OGweoP4Y3ZJOu8cSfyNxIGrrB9Gwy/rWGB6UUmdBHTydw8U0iSrX1w7P6lPJbdwMZ/8qPSKBu6rd3rKSyfHRYhC3uMaGygplNx9u8v2lZ9KpOGmiVYA/caa0GKPW7ZXCeP57qQhsLm7AavJUQg6TAQToinNTkoaRAgC/bNlbGzErFsCU4bGgLT0HNhQv4hsKZkLkTBkH098P5H1dA0yrjBAbC8hRPn+WgQ2ZFqBFrsOc3HIVB8scLpJC4ULI0dE4jp1r4jkjXy2u99kCvNBVjn4fY= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jun 03, 2025 at 10:29:59AM -0400, Steven Rostedt wrote: > On Tue, 3 Jun 2025 01:02:36 -0700 (PDT) > Hugh Dickins wrote: > > > Agreed that ramfs does not use swap, so calling swap_writepage() would > > be weird. But, thanks for the build fix Steve, but it cannot be right > > because return 0 says shmem_writeout() successfully sent the page to > > swap, and that has unlocked the page (or soon will do so). It should > > return an error (-ENXIO?), but I haven't checked what the callers do with > > Yeah, I figured it should return an error, but looking at the code I > couldn't figure out what the proper error would be. Then I also noticed > that the other stub functions just returned zero so I did the same. > > Perhaps add a WARN_ON_ONCE() if it is called without CONFIG_SHMEM configured? Or just make this module depend on SHMEM? I don't think it makes much sense to use it without being able to swap, and shmem can't swap ...