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Howlett" , Lorenzo Stoakes , Lu Baolu , "H. Peter Anvin" , Shakeel Butt , Suren Baghdasaryan , Thomas Gleixner , Toshi Kani , Vishal Moola , Vlastimil Babka , Will Deacon , iommu@lists.linux.dev, linux-kernel@vger.kernel.org, linux-mm@kvack.org, stable@vger.kernel.org, x86@kernel.org Subject: Re: [PATCH 1/5] x86/mm/pat: introcude cpa_lock() and cpa_unlock() Message-ID: <20260728143135.GG651302@noisy.programming.kicks-ass.net> References: <20260728-cpa-fixes-v1-0-2ed2352300b3@kernel.org> <20260728-cpa-fixes-v1-1-2ed2352300b3@kernel.org> <20260728142108.GW751831@noisy.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 70C2C2000C X-Stat-Signature: fskozxx3wh1up79bxqq73wjyrszcggrn X-HE-Tag: 1785249106-396171 X-HE-Meta: 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 r5uAvSw5 Y3KFzWoJXtIOIhndxSamQr10bO8mGYhsZQKhV9PUESU1MD9tgkUux/ZC2Kag9BvyuszDwL/TikCpj9iToB21Oq8KMkpiSh5o9UZiCz65RASg7lYlD1TrWpikSonFzk4o3FfW114obEgjs4KIqBqkIy+ONArnCF2QpruMl1CXd6cHMJLXsUQ02eX/DHxr+xKhPfuq5h7/7gdRhiVi7idUYiKfU4xKZ5uoDq5Eafm6C6Jo19v2URCWocbLpqKXKiSj90Hh5HNJn69XMPYdRNiurmShwwa/8m+31iy9v/86et2zNfij4a9hlbfQahJGgwGlFr5BGorGI5+PaSIcU6fnR6Sz+ELnVGhY/WhMGbDUo1mobeME= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Jul 28, 2026 at 07:30:27AM -0700, Dave Hansen wrote: > On 7/28/26 07:21, Peter Zijlstra wrote: > > There was already a patch merged that removed the shole debug_pagealloc > > exception. Is that not better? > > As I'm scanning through email this morning, there's another issue that > popped up with that patch. It's causing hangs on boot. > > It's looking like debug pagealloc not taking the lock is actually > functional, not an optimization. Although, I hesitate to say > "functional" and would prefer to use much less nice words to describe it. Yeah, lets figure out why that is before we retain this wart ;-)