From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 4B105CD6E4A for ; Tue, 2 Jun 2026 03:51:21 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 7B6596B0499; Mon, 1 Jun 2026 23:51:20 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 767966B049C; Mon, 1 Jun 2026 23:51:20 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 67CF66B04A1; Mon, 1 Jun 2026 23:51:20 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id 54C126B0499 for ; Mon, 1 Jun 2026 23:51:20 -0400 (EDT) Received: from smtpin30.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id EA43EC2964 for ; Tue, 2 Jun 2026 03:51:19 +0000 (UTC) X-FDA: 84833597478.30.027B9EB Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf14.hostedemail.com (Postfix) with ESMTP id 5443A100006 for ; Tue, 2 Jun 2026 03:51:18 +0000 (UTC) Authentication-Results: imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=YxSsoNn5; spf=pass (imf14.hostedemail.com: domain of osalvador@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=osalvador@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1780372278; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=RjMhCk/o5NC1phCHo9ITOCgxpvxbQwvB79yIHI8KxIA=; b=e84o18kakBP/hBWkkTLPXIoY4xhpOBrIgz6HcKXI6dpSAZBYXeW1mmvnxiQsoaBQwpbU75 cJdS2Cr2k2RKt/8J3v3V8Q8O/3RUiqn8tWtub+yDyQozi+ynqW52jw+beowRgFsVJA4YnK SPQduMP1cvI5YgwIWYY60/dtjlZryIw= ARC-Authentication-Results: i=1; imf14.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=YxSsoNn5; spf=pass (imf14.hostedemail.com: domain of osalvador@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=osalvador@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1780372278; b=CvDy2cN43b627Vy8uiP2iK2joZfxpCjWmtzhcxpfpUHBB5TPPsCFSm+agK/Dk/g5fVMqu1 3BmsCnr1yAFulcf+jMok0KVukAGfXYptWlbDsXlE4Pl83WuAhjpsmEspHu7h2CDeJlAt2y VboqoFiM6DWBn1MNPc5WTNez9tdzF2g= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 429FD437F8; Tue, 2 Jun 2026 03:51:17 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0F1C31F00893; Tue, 2 Jun 2026 03:51:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1780372277; bh=RjMhCk/o5NC1phCHo9ITOCgxpvxbQwvB79yIHI8KxIA=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=YxSsoNn5YJCuKxeKl6PAX++Bg1aMM2RevmuoB3R+3Asp5hkDYkYRJMv/TpeoLf9B7 Ro5GqUKqVtSJmc5PF+GpOiLc0azL+gPTApbXdxRHccH8Hr+f9xJ7//k0XcZqLOHvSi kGrbwecefO6SaCt1vbjnccI71sOts8z+Y7MsYvqGsWup39aDDNQTED3u4+lj/rv/8F syhtFXtiRdqG9CWJa2E8dieXcFf76SrQLQvLUGV2C2xznjLRecAhHWsKvgkLiwkJ25 xTybY/DuKaU+pdIyACHJmrYf48SqhRY4KcLhkA2h2XeK7eAcBCWailPapF06VTCHY9 SOQC8eSGQAvkQ== Date: Tue, 2 Jun 2026 05:51:03 +0200 From: "Oscar Salvador (SUSE)" To: Usama Arif Cc: Andrew Morton , david@kernel.org, willy@infradead.org, ryan.roberts@arm.com, linux-mm@kvack.org, pfalcato@suse.de, r@hev.cc, jack@suse.cz, Andrew Donnellan , apopple@nvidia.com, baohua@kernel.org, baolin.wang@linux.alibaba.com, brauner@kernel.org, catalin.marinas@arm.com, dev.jain@arm.com, kees@kernel.org, kevin.brodsky@arm.com, lance.yang@linux.dev, "Liam R. Howlett" , linux-arm-kernel@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, ljs@kernel.org, mhocko@suse.com, npache@redhat.com, pasha.tatashin@soleen.com, rmclure@linux.ibm.com, rppt@kernel.org, surenb@google.com, vbabka@kernel.org, Al Viro , ziy@nvidia.com, hannes@cmpxchg.org, kas@kernel.org, shakeel.butt@linux.dev, kernel-team@meta.com Subject: Re: [PATCH v7 1/2] mm: bypass mmap_miss heuristic for VM_EXEC readahead Message-ID: References: <20260601102205.3985788-1-usama.arif@linux.dev> <20260601102205.3985788-2-usama.arif@linux.dev> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260601102205.3985788-2-usama.arif@linux.dev> X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 5443A100006 X-Stat-Signature: g1isd5b5mk8fs143q4akkj8faxfpit65 X-Rspam-User: X-HE-Tag: 1780372278-55740 X-HE-Meta: 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 t0EXLPtz lECnsp6oCri3XuU21OjFNXm0xWJXr2xZ2BN8laWo++GyPlaHeBL4/zX237Ixopt994b/bTTvon/rmf+RFkbGQsK0MxeIUwmFGZYDQ408B2FMY/mNNE+/N9a68wtlhsS7We7GeDWv/MKRDaZop2Dqyhg5WGvizFdAh7zBx0zShElvniLn35iBWiW5N3KX01HA9bIsiDvxfyULBDtDcD4aAPTCuQrXrQcMTDVKedx083tfL9Bl9CNlrfixjtAGg/MFBg2KLCqFrmwu2faH95JbuDiSBmYEuRgA0REP3kxFheXLDy8oR0WYhAjZRFmBrn9mbwgBjwbDBiCA3ao7uPNSSaWFr6MRzyWhUd1BKtfoHETInw0f/9WSnL55YoaNfJkaP4wKB09dTLXEt3kW4Mas+61cSyg== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Mon, Jun 01, 2026 at 03:21:17AM -0700, Usama Arif wrote: > The mmap_miss heuristic is intended to stop speculative mmap readahead > when a file looks like a random-access workload. That does not fit the > VM_EXEC path very well. > > VM_EXEC readahead is already constrained differently from ordinary mmap > read-around: it is bounded by the VMA, uses exec_folio_order() to choose > an order useful for executable mappings, and sets async_size to 0 so it > does not create follow-on readahead. When VM_HUGEPAGE is also present, > the larger readahead is an explicit userspace opt-in. > > The mmap_miss counter is decremented from cache-hit paths in > do_async_mmap_readahead() and filemap_map_pages(). Those paths are not > always enough to balance the synchronous miss increments for executable > mappings. In particular, when fault-around is effectively disabled, such > as configurations where fault_around_pages is 1, filemap_map_pages() is > not reached from the fault path. The counter can then become a stale > throttle for VM_EXEC mappings and suppress the readahead behavior that > the executable-specific path is trying to provide. > > Skip both mmap_miss increments and decrements for VM_EXEC mappings, > matching the existing VM_SEQ_READ treatment and keeping the counter > accounting symmetric. > > Signed-off-by: Usama Arif > Reviewed-by: Jan Kara > Reviewed-by: Kiryl Shutsemau (Meta) Reviewed-by: Oscar Salvador (SUSE) -- Oscar Salvador SUSE Labs