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 8765BC5DF97 for ; Sun, 23 Aug 2026 23:01:45 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 447D16B0095; Sun, 23 Aug 2026 19:01:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3F9106B009B; Sun, 23 Aug 2026 19:01:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2E77E6B009D; Sun, 23 Aug 2026 19:01:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id 066AF6B0095 for ; Sun, 23 Aug 2026 19:01:43 -0400 (EDT) Received: from smtpin01.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay07.hostedemail.com (Postfix) with ESMTP id 700BA1603B5 for ; Sun, 23 Aug 2026 23:01:43 +0000 (UTC) X-FDA: 85134058086.01.4A249DD Received: from mail-qt1-f181.google.com (mail-qt1-f181.google.com [209.85.160.181]) by imf04.hostedemail.com (Postfix) with ESMTP id 92ADE4000A for ; Sun, 23 Aug 2026 23:01:41 +0000 (UTC) Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=gourry.net header.s=google header.b=u8UoykBT; spf=pass (imf04.hostedemail.com: domain of gourry@gourry.net designates 209.85.160.181 as permitted sender) smtp.mailfrom=gourry@gourry.net; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1787526101; 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=OBBDznrj/QvBtLL3STRylJUtnIkvdfK3qqt1IzYGCsg=; b=QhGOauZKRVWvpv+YB92pPUCUZ9u4weCWw9mqJEmd3KebV8+rhNvLjE3YVATWFkJVFudUSl pFnlCi3p0K+oozyMutxVz/BveYZf0pU8oWLxHByqWW8tO2dh4x9YVXw67U+gvc11rwXxA/ Kk/XZ9OYohHCSL9mtfYcz8RaSleAEuI= ARC-Authentication-Results: i=1; imf04.hostedemail.com; dkim=pass header.d=gourry.net header.s=google header.b=u8UoykBT; spf=pass (imf04.hostedemail.com: domain of gourry@gourry.net designates 209.85.160.181 as permitted sender) smtp.mailfrom=gourry@gourry.net; dmarc=none ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1787526101; b=SRQ9DxDp0229evJxhNbtPSbNiHpyRHahyEGWxF4/rrlWaDIA5pMEIt2qx7aCuf98B55gdK AGCM0xDoqAF7mM6pUtD6b+5ioJ4wTw6PBWh72H3mg3j6XhF03x/IscBRVtppUNoRFWcW/G 7D/XFL/iwB14wcGYFoEEliDc8A9Hun8= Received: by mail-qt1-f181.google.com with SMTP id d75a77b69052e-5276d598b96so13975481cf.3 for ; Sun, 23 Aug 2026 16:01:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gourry.net; s=google; t=1787526101; x=1788130901; darn=kvack.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=OBBDznrj/QvBtLL3STRylJUtnIkvdfK3qqt1IzYGCsg=; b=u8UoykBTGmv/xEoS/uDwP3QAbEL6pD5K9vQ97Cv3j58We3koB5Naasi5/8i1oGRPzb qu4rJHejrOVn056oE1slhSYhkQH+ONXFofQaVfnriUGHy2VyuoR+DM0+lDpZs2FP8HBF r4raAH6rFtamE27jETYYy8o6JiSjHA44Y88vIP+3n+iwMjwvkj6BvTTnAAYB4t7M8pTr K2LfmKq7umH5af8Ek815PegHB/HEAfobzV7tsncpPh5oLQgpf5OoMfS1yPNfqmg79rdx Fo71uR128kkTi/eeB0a6warZZr4/+I2Ew2hg/IpthpNd3KiSQNw896jlkTEyRDm7L1oO xeLw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1787526101; x=1788130901; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=OBBDznrj/QvBtLL3STRylJUtnIkvdfK3qqt1IzYGCsg=; b=sKjFDRDHnjZf8SX2ngtKc5A9nbcQmucbZMPz14PMBTs+Ov/e+lalJLtV6L0vNr2n0z Rci8EAFiyIeB6GLVllwrpZOzTwIBpbWCMhhqy8kJurUo+fQA5W5XGIRWOC2zZ/xleWAC K3w3aBMv8F6rPnn3NwJrsXqbkrQNeuvCF3Q5MfsNniFiIra5jJXS2a+ZTg/hHVycOAfn ENRdIUNPZ2r8qMy6f7MGVYvrSFuL/UUBgWoaHydTP1bkvltEnXwYFgwtdIAP+cmaZrLs ddDkieAsbWTZWZsMrAQetHNRT5cNAMhW5vAi/ofjCwyjetgBY3DgDmWgXZjkQ4ORN2wU WYPQ== X-Forwarded-Encrypted: i=1; AHgh+RorqDTYRPVi6dtWO0PhW1kjtfhAJpNejwr4CvCsk4mA5uHqByGJJBKb/7Zl2H2MDubgbjTg6b3c9w==@kvack.org X-Gm-Message-State: AFuF++mVPLgR+wb/PZfSDBhrD7gqELAyRTXFy6MfUBmXAYfCFPSSxfPn 3i5b7VJ29539lrtD6iuppaSR6wO4gvrQPfLx8OHt6b+G8wQCGqqOlNK/O9CID1tUq0s= X-Gm-Gg: AR+sD11iCOzzfxoigFp1YnKe1bwdpXG8TCfl4fdRpt827MLjjprH3/LF7eJ11vk0P/v khC0EmdffOgZBGWcEq9pKtIVuvcsBBowzmRoXsjP1gZVL1/Cw2wOTcAA+LP042b0L51AaFhvGas HY5UnaIQ74zSl9C9xFBZqCXCb9+qCAextS3SslL2yKiUrjU+tts3DtIii4gfUOQE3JPgD6lLHPy jIrDJcfoLcg1b0iQFA78GWY3BGNUOak2zroyVzeFxwU96DQhGU54+ACTyqZ4+reZTwp4D15ajRL NxbUv27y18kxv1xDqpp2VYDG3JKXpdECyejhChnvPUGh1Ozjp9WxFVqqmb2kh8so0tDHWFwuYF4 ciHjIqQ5mbd+OoJCeZobqJfnlQatoDHOoSmYiwZfzqe6QYC9arqr3YAwlqhBszmd1fVUq5Xi2s+ 4twXP2w8nvjW0Qra43Lu3Uih+N/jCom+HEeLIbJo9O1C/YU1jgrWf5jjXrAwdsh1PyAM/bjaTag Xm3u7seFGzPe0RGFueC4a47kQV2tXuSG567S9sQkLlYPAD4giBuoh0= X-Received: by 2002:ac8:6f14:0:b0:51c:b98a:2448 with SMTP id d75a77b69052e-52df56f9741mr225201801cf.9.1787526100658; Sun, 23 Aug 2026 16:01:40 -0700 (PDT) Received: from gourry-fedora-PF4VCD3F (pool-173-79-60-52.washdc.fios.verizon.net. [173.79.60.52]) by smtp.gmail.com with ESMTPSA id d75a77b69052e-52e09aca49dsm36057701cf.23.2026.08.23.16.01.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 23 Aug 2026 16:01:39 -0700 (PDT) Date: Sun, 23 Aug 2026 19:01:37 -0400 From: Gregory Price To: Andrew Morton Cc: Eric Dumazet , linux-kernel , syzbot+0dbf6d295b3350944f0b@syzkaller.appspotmail.com, David Hildenbrand , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Ying Huang , Alistair Popple , linux-mm@kvack.org Subject: Re: [PATCH] mm/mempolicy: Fix sleeping allocation in alloc_pages_bulk_weighted_interleave() Message-ID: References: <20260821170407.3721004-1-edumazet@google.com> <20260821104043.f692421fec915c0c5bc1fbe6@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260821104043.f692421fec915c0c5bc1fbe6@linux-foundation.org> X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 92ADE4000A X-Stat-Signature: n83gg16ogf1x4xfmny6spdne9qy1aonf X-Rspam-User: X-HE-Tag: 1787526101-702814 X-HE-Meta: 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 liG/Amcx Bw9izx78+6YB2Ijb2AxgiI3W1bcwIOTaIGfSUDLXrRR+f+HizaCn+V6BxW2BznJvjvW+3Lpxd3R8m1zCJpWsJNECZfW2RlIpuirtQ6JJFbxKXMUlVZ3Bp6+WZj1ZkM3gmsrXw+L+RW/Q0ckqWqe33BrvdGZ7iaz2AB4S41F667bpsnHvaQmVQAM3K/fAZQFPipqrEslgcoC2H9AX9PVR8VtG8zY9wnCUFOD67OQn2FdblyKYSAJ/jVLSf5EwGpqUkeG0xDQ9qrgYf+hPYWMiK31TK2gfCZpsCiXe5GhVqmGMYTMQlIHHBTRRiDmRsYELB2wtBMnIM03eBHJzk3LaKNceZLHDiOEi18ikMYVpwrMJFtwjOrJhmj03+PJl3mVxNaw8IP/v4q/F+yMwHmFKfDM/Bdq+3ePHOZBIpzJ/WACjtBhWe+V8K7HZtOt4/bQAJX4oaVSCTMfnCH3ep+MXCQwLH6lGz0he0uy13I2DeZGamq5TUCtgghCtYpZx2r5dOFPks Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Aug 21, 2026 at 10:40:43AM -0700, Andrew Morton wrote: > > --- a/mm/mempolicy.c > > +++ b/mm/mempolicy.c > > @@ -2688,7 +2688,7 @@ static unsigned long alloc_pages_bulk_weighted_interleave(gfp_t gfp, > > prev_node = node; > > > > /* create a local copy of node weights to operate on outside rcu */ > > - weights = kzalloc(nr_node_ids, GFP_KERNEL); > > + weights = kmalloc(nr_node_ids, gfp & GFP_RECLAIM_MASK); > > I wonder if we *really* need the local copy of state->iw_table. > Perhaps with appropriate care we can directly use state->iw_table in > here. > > How much would it hurt to expand the rcu_read_lock() coverage? > Ah, the current space we'd expand rcu read lock into is the actual allocation - which we can't do. Same with the spinlock. We can clean this up with a refcount + rcu_free and kill the allocation in the hot path. Will get something out this week. ~Gregory