From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 224A7606A321 for ; Wed, 11 Nov 2026 08:24:03 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=OViB9yQD Received: by kanga.kvack.org (Postfix) id 2A7116B05B0; Wed, 11 Nov 2026 03:24:02 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 256F16B05B5; Wed, 11 Nov 2026 03:24:02 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 16D8C6B05C3; Wed, 11 Nov 2026 03:24:02 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) by kanga.kvack.org (Postfix) with ESMTP id E629E6B05B0 for ; Wed, 11 Nov 2026 03:24:01 -0500 (EST) Received: from smtpin28.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay03.hostedemail.com (Postfix) with ESMTP id 7985AA0236 for ; Wed, 11 Nov 2026 08:24:01 +0000 (UTC) X-FDA: 85422150282.28.F4550A1 Received: from mta1.migadu.com (out-12.mta1.migadu.com [95.215.58.12]) by imf13.hostedemail.com (Postfix) with ESMTP id 8506620002 for ; Wed, 11 Nov 2026 08:23:59 +0000 (UTC) Authentication-Results: imf13.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=OViB9yQD; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf13.hostedemail.com: domain of baoquan.he@linux.dev designates 95.215.58.12 as permitted sender) smtp.mailfrom=baoquan.he@linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1794385439; b=DFWUknU7g8BfbqKfiuH6lrzHwsfC/TAferCfsgKWVaxfsVuPMYhYfh62bzo/TyVKjnCPTO UwI8cSWxua7JtiB84Lu4bsHVeb5JuokkOQltEoBAlPKiUoMEA2+0kytgk7ZPoNuCJGOazY WUyt55qNLoOUBbS1b0YXh/7pwLmrdSE= ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1794385439; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=1L3k0WCxEQM4MgkhzRov27MMiEEbLO/b0x9n2s0dbXg=; b=DdZTkAmHQpxMeSoazsFVC3kjKHhI2J4xJqBmXjg8hT5dmNtTJYlTDYn4+Yl96gP2B5ybWO /yQMgucgGbieQIKsc9TogvjkVBWajN8HIZ7nHYZLpC77GAf5UCGYX4FQXR1mVqK6hhaklo 33HLArrxt1+oVX7FwbONx5pZm5ZsakY= ARC-Authentication-Results: i=1; imf13.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=OViB9yQD; dmarc=pass (policy=none) header.from=linux.dev; spf=pass (imf13.hostedemail.com: domain of baoquan.he@linux.dev designates 95.215.58.12 as permitted sender) smtp.mailfrom=baoquan.he@linux.dev X-Envelope-To: linux-mm@kvack.org DKIM-Signature: a=rsa-sha256; bh=2a1uCTTqQgMgnglTolQFYLYOCZnjaTu0ja8XTo4UI8w=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1794385438; v=1; x=1794990238; b=OViB9yQDa9oR9BNbWZeyfr0i3TkhY0DKdIYxCAoW85Fm+rVoc9rB9No28BBCRQiWouU4xRiM 36rYEn55/N7f0iTRLAGRdkAmERJLijPRGmu+6vddtFGlwF/f1+KrNWyG9ni7L+crU72jgslvrwV dE5ru9su7q8WCPejFag+8/pc= X-Envelope-To: linux-mm@kvack.org Received: by mta12.migadu.com with ESMTPS id 6852131fc591cc1f; Wed, 11 Nov 2026 08:23:58 +0000 X-Mizu-Trace-ID: 6852131fc591cc1f X-Migadu-Flow: FLOW_OUT Date: Wed, 11 Nov 2026 16:23:48 +0800 From: Baoquan He To: Kairui Song Cc: Baoquan He , linux-mm@kvack.org, akpm@linux-foundation.org, baohua@kernel.org, shakeel.butt@linux.dev, axelrasmussen@google.com, yuanchu@google.com, weixugc@google.com, david@kernel.org, rostedt@goodmis.org, mhiramat@kernel.org, hannes@cmpxchg.org Subject: Re: [PATCH v2 3/4] mm/mglru: skip cold PUD subtrees during aging Message-ID: References: <20260901063755.1519710-1-hebaoquan@kylinos.cn> <20260901063755.1519710-4-hebaoquan@kylinos.cn> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Queue-Id: 8506620002 X-Rspamd-Server: rspam12 X-Stat-Signature: 7st8oot6m69s6rehx1f7imwgfnx5zz3s X-Rspam-User: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-HE-Tag: 1794385439-485653 X-HE-Meta: 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 MxNXDyGQ 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 11/11/26 at 03:38pm, Kairui Song wrote: > On Wed, Nov 11, 2026 at 3:19 PM Baoquan He wrote: ...snip... > > > I think we can drop the PUD ptr walk entirely. The filter only > > > needs a stable identity for the range walk_pud_range() is iterating, > > > and (mm, PUD-aligned address) gives that on both sides: > > > > > > walk_pud_range(), test and update alike: > > > (void *)((unsigned long)args->mm ^ (addr & PUD_MASK)) > > > > > > lru_gen_look_around(): > > > (void *)((unsigned long)vma->vm_mm ^ (pvmw->address & PUD_MASK)) > > > > > > Will this work? Also I took a look at the hash algorithm of this too: > > > > Sorry, missed this mail too, thanks for great suggestion. > > > > Yeah, it's a much better way to do pud level filtering. I will > > switch to it in v3. > > Great, we should have a super fast O(1) key calculation then. > > > And the same idea on PMD has been merged, your suggestion is earlier > > than it. > > 65a9bf08a3e4 mm/mglru: don't use stack pointers when walking PUD and PMD tables > > Not sure if I understand this wrongly, but 65a9bf08a3e4 is fixing a > potential stale stack value, not changing how PMD keys are calculated? Ah, my bad. It indeed doesn't change how PMD keys are calculated, I thought about it wrongly on whether pmd key can be calculated the the similar way as pud. Seems the answer is not worthing.