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Received: from willy by casper.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1vx9KZ-0000000A00h-2iCh; Mon, 02 Mar 2026 19:53:27 +0000 Date: Mon, 2 Mar 2026 19:53:27 +0000 From: Matthew Wilcox To: Joshua Hahn Cc: Alexey Suchkov , akpm@linux-foundation.org, dywoq.contact@gmail.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] [PATCH v2] mm: initialize 'seq' in gup_fast to remove -Wmaybe-uninitialized warning Message-ID: References: <20260302193405.37961-1-dywoq.contact@gmail.com> <20260302194836.2932150-1-joshua.hahnjy@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260302194836.2932150-1-joshua.hahnjy@gmail.com> X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 8C1DB80002 X-Stat-Signature: yhyay3yfidn4xrfq77cufgtsakhcauyu X-Rspam-User: X-HE-Tag: 1772481209-61597 X-HE-Meta: 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 bPYHF0Jf Tn2zykZ+Co1vd+D36x7seznVY5Sp+qmXQk/XpEnLgX7K0IzWlKONf2/MD/cHoW1j51OqlYwE6OQACgSyY4/RI73KdqE6mxMyDlU2qeKkC2SbhrGow6Pm1U3BhPiy7X82arWhng8meJt+gpts09Z0w8jBm0fBJCjIRCTvqnFehhP5Ev+SQOih//bKNDvu0Btq5QhUrADNArFxLlGOZwYbg8wl6/8DEQUZUDKc/o1lGf/Sy+mEwDGXYhm3qJU81VWv/1ROSD16eU34n5OpT4YbMRUrjjbI2uYRGTYOIlT2sKjLhuyyGgxorbOufmISKrg8L1oajfSNSd+xWzjzgWuDLLbdL4TwK0lKVXjFkxo2qHReXEoA= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Mar 02, 2026 at 11:48:35AM -0800, Joshua Hahn wrote: > Unfortunately I think that this patch is still unneeded. The variable seq is > used in two places, raw_seqcount_try_begin and read_seqcount_retry, and nowhere > else in the function. Both are guarded by if (gup_flags & FOLL_PIN). Yeah, historically GCC wasn't great with that pattern. It failed to notice that the condition was the same and so there was no path through the code that would use an uninit variable. Hence my question about what compiler version he's using to see whether we can disregard this because it's an old compiler that we don't support any more.