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 E66E1FF8873 for ; Thu, 30 Apr 2026 16:16:09 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D57F26B0088; Thu, 30 Apr 2026 12:16:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D2E576B008A; Thu, 30 Apr 2026 12:16:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C45626B008C; Thu, 30 Apr 2026 12:16:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id B0EF16B0088 for ; Thu, 30 Apr 2026 12:16:08 -0400 (EDT) Received: from smtpin12.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 5C8F61270EB for ; Thu, 30 Apr 2026 15:04:26 +0000 (UTC) X-FDA: 84715543332.12.672CFD7 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf15.hostedemail.com (Postfix) with ESMTP id 1B48EA0017 for ; Thu, 30 Apr 2026 15:04:23 +0000 (UTC) Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=qB3bjfQ0; dmarc=none; spf=pass (imf15.hostedemail.com: domain of akpm@linux-foundation.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1777561464; a=rsa-sha256; cv=none; b=d2d0n3p0ZPnut/iFnigVigPAQv3apLvpEEkFIiwxAky/E0md1spAyqZwTrxF2X48eBW9jK jrY6rejrzeg8ld+tC1fmInDmul6LvCYgGkR2bArwnNmnRvGkENtcRORtZabIxInfZKRL/q mE6XWmZJ0ojbPFlXrdxX+LkD1Ls+40I= ARC-Authentication-Results: i=1; imf15.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=qB3bjfQ0; dmarc=none; spf=pass (imf15.hostedemail.com: domain of akpm@linux-foundation.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1777561464; 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=PuFT8PznD3oZL+h6zh/YmyaAdPxjqm1lCU9/tnSkZ3w=; b=fqa532xZQ6g4NT3d73SNc3i4UUIvzEpn4RuRviA5iK79GzbWaVeXed76mQx4rqnq2II3MF HFJuXvlCKZtQ6TfzEGo6u+QpMr8YjYIDjjrDKRCB8IIlIbuFILVWyVsLo2HJ6WI920p6uV XkiDfBnQpOrUk8fwXkG/1I0qz5uB3ls= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by tor.source.kernel.org (Postfix) with ESMTP id 3458760582; Thu, 30 Apr 2026 15:04:23 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6F30C2BCB3; Thu, 30 Apr 2026 15:04:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1777561462; bh=DPoNqejj7L+Qi9qzpFKoImHPM8d005RnQS3YCCnbqjM=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=qB3bjfQ03/ociA0V93GPGwkYzdmJ2oXxS3aBuCq3uttB8MlXl9/nCBLKxPuSOayon vCH6Wu3MDdLDNfpfk6pkp2YsXoJPWKYByBXQ99a3w6f6/yx48O04urQTxCBnvZ+0oN 6VE5InbibO8ND/EcmXHJ2X/Mwnd0XUKBk9VfhxHo= Date: Thu, 30 Apr 2026 08:04:21 -0700 From: Andrew Morton To: Zi Yan Cc: David Hildenbrand , "Matthew Wilcox (Oracle)" , Song Liu , Chris Mason , David Sterba , Alexander Viro , Christian Brauner , Jan Kara , Lorenzo Stoakes , Baolin Wang , "Liam R. Howlett" , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Shuah Khan , , , , , Subject: Re: [PATCH v5 01/14] mm/khugepaged: remove READ_ONLY_THP_FOR_FS check Message-Id: <20260430080421.902b8e38df2a3b79421396bf@linux-foundation.org> In-Reply-To: <4C10A739-4931-4922-B2C2-245A610C0120@nvidia.com> References: <20260429152924.727124-1-ziy@nvidia.com> <20260429152924.727124-2-ziy@nvidia.com> <4C10A739-4931-4922-B2C2-245A610C0120@nvidia.com> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: z5bzbf8hc81zwezbh9138okeqbbky8ij X-Rspam-User: X-Rspamd-Queue-Id: 1B48EA0017 X-Rspamd-Server: rspam07 X-HE-Tag: 1777561463-701195 X-HE-Meta: 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 Kw+UGhZx v6e5bMYriQvLu+27IWy/hkwcR22HyzRBcp+8yNBwyDRgKlfvkGjAjZoQ209Hir5HfubTeBd7T557xDuZlxy7h5iBKyLGBLWw3Z2L7GrE5ucoRvDN6Aw4UTyTrxb8E3eT0+t1h2AlNjrYc0fxKp9Rudswv/t4HK49nQWt99SZT8whlgbQAJe6XMqj+NoalZmVvxv3zmQittrICT2VH93HkSGZz/mnpPLv+xuDMCFIDNRiHX7d0ssOASM+hKoM6bn7dmPKWPBHLcI32fJY49fYmAi9uXQ== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Thu, 30 Apr 2026 10:37:52 -0400 Zi Yan wrote: > + * MADV_COLLAPSE ignores shmem huge config, so do not check shmem > > + * > > + * TODO: once shmem always calls mapping_set_large_folios() on its > > + * mapping, the shmem check can be removed. > > + */ > > + VM_WARN_ON_ONCE(!is_shmem && !mapping_pmd_folio_support(mapping)); > > sashiko asked: > Is it possible for userspace to intentionally trigger this warning via > madvise(MADV_COLLAPSE) on an unsupported read-only file? Although in > a later commit, modified file_thp_enabled() will prevent this. > > Answer: > It is possible when CONFIG_READ_ONLY_THP_FOR_FS is enabled, but it is > unlikely a kernel will be shipped at this exact commit. Yeah, let's not worry about minor bisection holes.