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Mon, 21 Apr 2025 17:35:50 +0800 (CST) Date: Mon, 21 Apr 2025 17:35:46 +0800 From: Ruihan Li To: Andrew Morton Cc: Mike Rapoport , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Ruihan Li Subject: Re: [PATCH v2] mm/mm_init: Don't iterate pages below ARCH_PFN_OFFSET Message-ID: <7eunuizzdfpgskxrfmngklrq632szzgscp6agwxsl7wsodpdqn@vnyg7d3v6tmh> References: <20250419122801.1752234-1-lrh2000@pku.edu.cn> <20250420135709.732883ee775ad8b41fb668ca@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20250420135709.732883ee775ad8b41fb668ca@linux-foundation.org> X-CM-TRANSID:54FpogC36oRyEQZopzRfAA--.30840S2 X-CM-SenderInfo: yssqiiarrvmko6sn3hxhgxhubq/1tbiAgEIBWf35XUDOwAYsu X-CM-DELIVERINFO: =?B?e7M+XaaAH6dYjNjDbLdWX9VB7ttaQFyXTaecYZzOeDisy/krtsX5TsLkpeAzENeCPc 0+BDdXjm5Mlm64oODP/CxX7Cf2JIhgSgyACdMUW+7z6NjTyzqRnhhfG2Fy/TDcNc2v3qRm vOLh3hF4Q3MRpa5gnRFIj2rOMEQnOcipZfzoYUAV81A49P3JdCzVwLiTrUlRWg== X-Coremail-Antispam: 1Uk129KBjDUn29KB7ZKAUJUUUUU529EdanIXcx71UUUUU7KY7 ZEXasCq-sGcSsGvfJ3UbIjqfuFe4nvWSU5nxnvy29KBjDU0xBIdaVrnUUvcSsGvfC2Kfnx nUUI43ZEXa7xR_UUUUUUUUU== X-Rspam-User: X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 4B3774000D X-Stat-Signature: yj3r7w8woz9dmyq3txznzmu839dotont X-HE-Tag: 1745228161-876899 X-HE-Meta: U2FsdGVkX1+QMsHBaxJtQC0VQsVkeJTurVE+3JYkHXmIrpLOKr7dCe2cM+deIZ8FOa+hrcvQMF7vbwsXoMzECqvOIVyqhDcZmmJmz5eBcnLwYSwPpN6uwXfxeYDxN8BpbgxihM/r61FkliLwJKgdenSaPBsm7YfhcYLJgv7j7GDdX9Mw1kuncYz6Wr+Lwt6xbFmUYUk3xMeP6m/cgdbjYfJXMQVD5sPmNe3vzRxd+Y1eCcccrjiTQsheolvnzKg/K6jgNR1dMT43rURVzDZRN2BleRxVcgALJ9THviookLiwlHnV8H69HwqhU4eF76FSguQEpW3I3Vv/ta7JZ+GR0k+CMacJOrJBjUSbzKmvbjkUP5UdU4GDODJUzl7eGeh9Q6jK0CXxKHc/AbXb15hDPOMXR9rtLA4GrNS8AjSzicOC0oFBAlVBaQUQmfDoeFlj2KlgJJ8OwstMynwYlEHn6snC9G409kT8nLVQ4UDnlSZfQLybXloSZRBI5A3TOiBbHa0bsVN+cZPO8bcH4XuEUm+dZPYfVH0DyFVswff/M1Fvo8ZkU6FMyp9HcDkSi8Aoz1gDTWEObrl8ohlMgrvZ156rSmNndbeKhzaanADhSbm3W37Iqr550rb2KV0y73woywmKkPe6ELnqnQS2OU8O5wRcO8l552RfQsRM7yqCcLADRJZV//krM6GuGutwGMDGImoFTsnTu53sEi09bbxq1A50CFxDXUt5dsEvA6RyVM355xYSKOm8IHIFsQKUt5PBZbo/uJQokCEdkLbMgjhioRbQ/gREACXSf5hBxGzPrkkSUbobP+a1R1bJFqVIf2MgKzTQL7/CVvBMp3hkKe8zDwKcTovUcDI6sOZtiEjs+UVPoxL22RhrH4svbw7ltlemOCwhRzCKBLu/AzBbI7WxSQl9u/qwOZjXWIGYliYY6sNv2TAGX1Gdrm71F3AuuETPzleGiAcX8Or1a4zRJ2w QzFVngez baEjnqDPT5BRoaJ1rHQhu1tVDR/fCXeKiemNxeRp73Sr7MOP1SLHQ136tfOM3yOj7O258sDveqKdNV5swvFNgc2Urq9nybFVcNyr8SW5Vv15d6E8O65FQLRvD1ninZhibXQ/5s5sJR3FyP0x/Tk30OkjAKyx3PY3xHKKm7ZZFLhWJNgBBNW1Sv5TjudAj69fokRjFEIvd6mcALaYb7AnGp7cjH3jCuuT65lrbWOTfBmfGWiYqaA6/FwekzhWFrE41etUr+KbMARkzXjIIl3n+WopdKEgKOtVa8m1l2kwPHwILRtFYaHML47VdJrLzKAV8r2mC4tm9TGYmCryiJeGzTcFL9w== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000076, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi Andrew, Thanks for your review and for taking the patch in the -mm tree! On Sun, Apr 20, 2025 at 01:57:09PM -0700, Andrew Morton wrote: > On Sat, 19 Apr 2025 20:28:01 +0800 Ruihan Li wrote: > > > If ARCH_PFN_OFFSET is very large (e.g., something like 2^64-2GiB if the > > kernel is used as a library and loaded at a very high address), the > > pointless iteration for pages below ARCH_PFN_OFFSET will take a very > > long time, and the kernel will look stuck at boot time. > > > > This commit sets the initial value of pfn_hole to ARCH_PFN_OFFSET, which > > avoids the problematic and useless iteration mentioned above. > > > > This problem has existed since commit 907ec5fca3dc ("mm: zero remaining > > unavailable struct pages"). > > > > Signed-off-by: Ruihan Li > > --- > > Link to v1: > > - https://lore.kernel.org/linux-mm/20250418162727.1535335-1-lrh2000@pku.edu.cn/ > > Changes since v1: > > - Removed the unnecessary Fixes tag. > > Why was the Fixes: considered unnecessary? It seems to be useful > information? > To clarify, I only removed it because I got comments saying that this patch doesn't really fix a BUG (well, that statement depends on how one defines a BUG: it's a real BUG in my scenario, but maybe not a BUG for many other scenarios): https://lore.kernel.org/linux-mm/aANN0rwxcajUtFXs@kernel.org/ Since I don't know if there are other rules that apply here, I followed the review comments to remove it. Another possibility is that I misunderstood Mike's original comment? Sorry if that happens. Thanks, Ruihan Li