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Thu, 24 Sep 2026 00:28:23 -0700 (PDT) From: Mikhail Gavrilov To: David Hildenbrand Cc: Andrew Morton , Dave Hansen , Lorenzo Stoakes , "Liam R . Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Vishal Moola , Ingo Molnar , Lu Baolu , Jason Gunthorpe , Steven Rostedt , x86@kernel.org, linux-mm@kvack.org, regressions@lists.linux.dev, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm: don't defer freeing kernel page tables while booting Date: Thu, 24 Sep 2026 12:28:19 +0500 Message-ID: <20260924072819.33277-1-mikhail.v.gavrilov@gmail.com> X-Mailer: git-send-email 2.55.0 In-Reply-To: <41a59ba9-039e-454f-8d31-f647db802ada@kernel.org> References: <41a59ba9-039e-454f-8d31-f647db802ada@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 7F344180002 X-Rspam-User: X-Stat-Signature: 66e7ofwkfsb4to1jacbtmkjsmz5d1ety X-HE-Tag: 1790234905-992892 X-HE-Meta: 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 5Vd+1hLR 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 9/24/26 09:07, David Hildenbrand (Arm) wrote: > Should we instead simply skip the > > schedule_work(&kernel_pgtable_work.work); > > and rely on anybody freeing stuff later to just free that one alongside? > > That avoids throwing in more freeing handling. Yes, that is simpler, and the early table then goes through the same IOMMU flush as every other one, so there is no need to reason about what an IOMMU can see during boot. The only cost is that it waits on the list until the next kernel page table is freed after boot. I'll send a v2 that way once I have booted it here.