From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D8CF03D649D; Tue, 30 Jun 2026 16:42:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782837733; cv=none; b=XNxvxeiqdOq8vefO3OfwYZsd3PodIJLOrgSL006TOVba93GylJ0NaBYkWHBYgtOgfM/WG+aRQfdFSu5PDdjhNCUpcb4+LAHELWawSrWgUoe7mskIzNaGY8nYr5pbCsirFW9b+M/oGgZk2jQFwnd5963N1OAgPY4WU3m8MkrSlQE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782837733; c=relaxed/simple; bh=IYQJYJU1FvhLnMiRCIMG8wiz45ZDbxiCBIOHa3w+0Mk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=I0RF0dKlRRYio02vtacEy1otc+Gj7Fi4s13CzzPmGwbLhGDcy16WrjygumbRRzYvoyOlQB9nlxlliRFsNDZgEBNq+LQ4aitlu+YSspd3PVI3TnUumEAhlMt+kbjWqUiGw0DW/sE1OadRn1Ej6uPxrK7aOITf2zD41CvZy+L5c6M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Mpjj1UpA; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Mpjj1UpA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 90ECF1F000E9; Tue, 30 Jun 2026 16:42:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1782837731; bh=FGaQANRuz7ppZV2PSxCdI1jyGhFNKQCFfZRkpjfHIx4=; h=Date:Subject:To:Cc:References:From:In-Reply-To; b=Mpjj1UpA9JvWJDddJxrWhkw/KgM7NeF2WyUc6ixJCeX2ovt8ol68V2rJtBbTDtFT8 Z3cPZHdMgHR6zxn+yzaF5QBu/zgeJa8rHKgCHWal563uBDK9MIrN+LfWBCR+uPMIzn TP2mR3hru6thL0WQDc7fJRQeuMyyCvOHj4WhMkdLmYrA/GIo8ktjRrxZg/PNw/51q7 W1ChdE9N1cO+m+vXnjmwi6f7WU7ztLvqVWettq9woeTZNmbmwsgji+rmzjbpXB4EYS 9BVHOhiuEUkBE6N41SiXWiAXR0daUye9ldy5nfBo5xfIchE/ceRZdcnk467CQ8x/iD JsDO+oNp5EdeA== Message-ID: Date: Tue, 30 Jun 2026 18:42:04 +0200 Precedence: bulk X-Mailing-List: linux-rt-devel@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 06/16] mm/page_alloc: relax GFP WARN in nolock allocs Content-Language: en-US To: Brendan Jackman , Andrew Morton , Suren Baghdasaryan , Michal Hocko , Johannes Weiner , Zi Yan , Muchun Song , Oscar Salvador , David Hildenbrand , Lorenzo Stoakes , "Liam R. Howlett" , Mike Rapoport , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Ying Huang , Alistair Popple , Hao Li , Christoph Lameter , David Rientjes , Roman Gushchin , Sebastian Andrzej Siewior , Clark Williams , Steven Rostedt Cc: "Harry Yoo (Oracle)" , Gregory Price , Alexei Starovoitov , Matthew Wilcox , Hao Ge , linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-rt-devel@lists.linux.dev References: <20260629-alloc-trylock-v3-0-57bef0eadbc2@google.com> <20260629-alloc-trylock-v3-6-57bef0eadbc2@google.com> From: "Vlastimil Babka (SUSE)" Autocrypt: addr=vbabka@kernel.org; keydata= xsFNBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABzSNWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBrZXJuZWwub3JnPsLBsAQTAQoAWhYhBKlA1DSZLC6OmRA9UCJPp+fM gqZkBQJqFFy6GxSAAAAAAAQADm1hbnUyLDIuNSsxLjEyLDIsMgIbAwUJGtCBUAULCQgHAwUV CgkICwUWAgMBAAIeBQIXgAAKCRAiT6fnzIKmZJIUEADFx/tREzUImHrEwVHeSvDFmA7tJysI UVrlvrM09E7GIuzphzv7jYmo8n3ANpCczLEVr4G0syYQdTigaZgv3+FQDIIzhKih1IHhu1Ei XHlywNWKnQxxQEUNi5Mwx43wQz5XVw9F1A7gtKBKNtfogO511hAbrzagrYajyQacEJ/+sfhZ 9Da8ltHIXD8pcYaHUfQgEusCgmEd9+KrUwrTbckFKmYq5chuE6yJ4J0EmWknL096jIE6CnzF FRslQ3B1UKDjxVsm1ZHfir5NeWszLkTvGFsddFaWTgh8UycESG6VQzKXjjewXu2pG7YQYRpj QKm1W5X2TkwWkXRBZTmfmbhxIUMh3+zf5wQ463rSmDN/8v81tdqBtAW6rH/kzg1GvkaTHXn0 507yEHFzBksk2viAuIxxr7km8+/KARYLIdGtx30EG8cKzAUZOK6WqxtNCsXUJNrVE8CWrCaD icoNu7Fs1c5hmPHdSTnU48ce67449DdnO4neLSNhRiGlMHJgfJUmgrxu/hcYeOZ3haWmEQ2w uW1Mh01OHi8QZHCEyAbABrPs9GUgccc/4eYXX9hIgxfSkYzn8f+8NuIFPWl/0uTvjgqU29FQ SbzOLxHq9439Ox40G5mS5eZXRGxITYR+6TXvRGI6P/264jvflnr/pDGUttaikU+0W+1uxgKH cmYbEc7ATQRbGTU1AQgAn0H6UrFiWcovkh6EXVcl+SeqyO6JHOPm+e9Wu0Vw+VIUvXZVUVVQ La1PQDUi6j00ChlcR66g9/V0sPIcSutacPKfdKYOBvzd4rlhL8rfrdEsQw5ApZxrA8kYZVMh FmBRKAa6wos25moTlMKpCWzTH84+WO5+ziCTsTUZASAToz3RdunTD+vQcHj0GqNTPAHK63sf bAB2I0BslZkXkY1RLb/YhuA6E7JyEd2pilZOrIuBGl/5q2qSakgnAVFWFBR/DO27JuAksYnq +aH8vI0xGvwn75KqSk4UzAkDzWSmO4ZHuahKtQgZNsMYV+PGayRBX9b9zbldzopoLBdqHc4n jQARAQABwsF8BBgBCgAmAhsMFiEEqUDUNJksLo6ZED1QIk+n58yCpmQFAmfIHFQFCRYU6J8A CgkQIk+n58yCpmS2PA//bqN1LfcotmArgElsa+0EGZSQlYgK48pm8WAeTXTngudP9IJ4SuKY HR5RNjHcBeqN+Me0zxRqYzRb8nGanHEkDyf4Im8DQM8d6vbyU+FcPmG4skud4kgS1zMHnlVd SXfSIwKC/hKgdHG8aBV7545Lz9X6Iohea+94wneD0aw/hqF+QWewGZhWJriWAZtvEkzNjQOi 4U9F/trLten/x7bpphDSnDMKJtITbtzATT1Dq7o7VpIUK1nCTQALMuMjKCdi8OdU/+V+R3O4 0PXWvX8qrvqYapVbZ+9KqT74FsuB0Ya9uXwgBF2Q6cRuETZk5vqaqKxzqoQZCO8AOz/58j6O 2RHNy/mZEN+7tJ5Tsq42zVJ4jxsT8b9YplavCMsnBgDeRWhcbYhCyttoL7nYISyWg4kQYZ/P wIV3OuNv2f8iKYsxNsRuClOAF82+gvqOy1/1pprFjy8uo2pkoOrb63aOP3vO5VHnRKgra6dq NcaZ+c6J4H+nEJGi2SkHAUJz5oBzuThvPudLvPA/SK8sKoM01IRxSihev/S/5WLazXB1PGem OCbvzC1IjWJJraxiDJ5IygokapUa2RP7+WBR22skQ3SSl6G107QgWKSyTOGWEaRmV53vxQLV jXuCmzSSasTL60zq5yGrT4/DYQVSNEUiUbG4pYekxJujNeEDkUlky0Y= In-Reply-To: <20260629-alloc-trylock-v3-6-57bef0eadbc2@google.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 6/29/26 15:11, Brendan Jackman wrote: > This WARN forbids setting other flags than __GFP_ACCOUNT but we > unconditionally set the ones in gfp_nolock so they are certainly fine > for the caller to set. > > There are other GFP flags that are almost certainly fine to set here; > Willy noted GFP_HIGHMEM, GFP_DMA, GFP_MOVABLE and GFP_HARDWALL. But, > nolock allocation is rather special, so be conservative to try and > ensure we have a chance to think carefully before nontrivial new > usecases arise. > > Suggested-by: Matthew Wilcox > Link: https://lore.kernel.org/linux-mm/ajS96fWbG4dzP3u3@casper.infradead.org/ > Reviewed-by: Suren Baghdasaryan > Signed-off-by: Brendan Jackman Reviewed-by: Vlastimil Babka (SUSE) > --- > mm/page_alloc.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/page_alloc.c b/mm/page_alloc.c > index 8d409d075e3e9..9cb3f1665b41b 100644 > --- a/mm/page_alloc.c > +++ b/mm/page_alloc.c > @@ -5355,7 +5355,8 @@ struct page *__alloc_frozen_pages_noprof(gfp_t gfp, unsigned int order, > return NULL; > > if (alloc_flags & ALLOC_NOLOCK) { > - VM_WARN_ON_ONCE(gfp & ~__GFP_ACCOUNT); > + /* Certain other flags could be supported later if needed. */ > + VM_WARN_ON_ONCE(gfp & ~(__GFP_ACCOUNT | gfp_nolock)); > if (!alloc_trylock_allowed()) > return NULL; > gfp |= gfp_nolock; >