From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 76E3C881E for ; Sun, 4 Feb 2024 07:20:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707031242; cv=none; b=g/llX/I/ZCkLH7RAxrwvCzS3rKT2Jz/6ycCbhzuC0ON6Sf+oqAoXeAoM8gRXKlxeMjwv1rhxAM9PuIUBsk1NA7hBxHKV5oLbBiKtdhiNxnRLAkXW3m8ttkFUnqZjOBhzq/S8b0EOwdjClZ0HGvJbypwfZkWlfHXhhEX5mJERCIM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707031242; c=relaxed/simple; bh=d18BmcrCQi+45ji8bTBBMbkUIIYVl8LEjCfpRjRkkmQ=; h=Date:To:From:Subject:Message-Id; b=tVYPYdilQ+ME4p6vN0H7/8CskYMZjeXp1NC/la36VBubDXEoADdoztqtqOayrK5QAAY5r8mHklXsChW8Uv0DIKLzG5+Rqo7EvRg7n9En40CBnpG/qF3x2HTNGTYGo26zr20nle/NMP5hUc5bdJ0EpLgpXKTg8Kpaii9Bal9bdTQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=RhNsOpUs; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="RhNsOpUs" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D98F0C43390; Sun, 4 Feb 2024 07:20:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1707031242; bh=d18BmcrCQi+45ji8bTBBMbkUIIYVl8LEjCfpRjRkkmQ=; h=Date:To:From:Subject:From; b=RhNsOpUsA83nvFzGW49A1GVqQtR+GACUZYY9BLlw8yRYS2agNwFY4Di/q9ztH7rPX 8xt10opYT3o72vBZrraFb963J5AJ1tPv2jhqsb5fSQYaOFqaJsqES3WNna7rvmIFtj hb6IsFmnKVMWrggZCkjENT5DGQyJQoCO4XUP7DnQ= Date: Sat, 03 Feb 2024 23:20:41 -0800 To: mm-commits@vger.kernel.org,ying.huang@intel.com,sthanneeru.opensrc@micron.com,ravis.opensrc@micron.com,rakie.kim@sk.com,mhocko@kernel.org,hyeongtak.ji@sk.com,honggyu.kim@sk.com,Hasan.Maruf@amd.com,hannes@cmpxchg.org,gregory.price@memverge.com,dan.j.williams@intel.com,corbet@lwn.net,gourry.memverge@gmail.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-mempolicy-refactor-a-read-once-mechanism-into-a-function-for-re-use.patch added to mm-unstable branch Message-Id: <20240204072041.D98F0C43390@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/mempolicy: refactor a read-once mechanism into a function for re-use has been added to the -mm mm-unstable branch. Its filename is mm-mempolicy-refactor-a-read-once-mechanism-into-a-function-for-re-use.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-mempolicy-refactor-a-read-once-mechanism-into-a-function-for-re-use.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Gregory Price Subject: mm/mempolicy: refactor a read-once mechanism into a function for re-use Date: Fri, 2 Feb 2024 12:02:36 -0500 Move the use of barrier() to force policy->nodemask onto the stack into a function `read_once_policy_nodemask` so that it may be re-used. Link: https://lkml.kernel.org/r/20240202170238.90004-3-gregory.price@memverge.com Signed-off-by: Gregory Price Suggested-by: "Huang, Ying" Reviewed-by: "Huang, Ying" Cc: Dan Williams Cc: Hasan Al Maruf Cc: Honggyu Kim Cc: Hyeongtak Ji Cc: Johannes Weiner Cc: Jonathan Corbet Cc: Michal Hocko Cc: Rakie Kim Cc: Ravi Jonnalagadda Cc: Srinivasulu Thanneeru Signed-off-by: Andrew Morton --- mm/mempolicy.c | 26 ++++++++++++++++---------- 1 file changed, 16 insertions(+), 10 deletions(-) --- a/mm/mempolicy.c~mm-mempolicy-refactor-a-read-once-mechanism-into-a-function-for-re-use +++ a/mm/mempolicy.c @@ -1905,6 +1905,20 @@ unsigned int mempolicy_slab_node(void) } } +static unsigned int read_once_policy_nodemask(struct mempolicy *pol, + nodemask_t *mask) +{ + /* + * barrier stabilizes the nodemask locally so that it can be iterated + * over safely without concern for changes. Allocators validate node + * selection does not violate mems_allowed, so this is safe. + */ + barrier(); + memcpy(mask, &pol->nodes, sizeof(nodemask_t)); + barrier(); + return nodes_weight(*mask); +} + /* * Do static interleaving for interleave index @ilx. Returns the ilx'th * node in pol->nodes (starting from ilx=0), wrapping around if ilx @@ -1912,20 +1926,12 @@ unsigned int mempolicy_slab_node(void) */ static unsigned int interleave_nid(struct mempolicy *pol, pgoff_t ilx) { - nodemask_t nodemask = pol->nodes; + nodemask_t nodemask; unsigned int target, nnodes; int i; int nid; - /* - * The barrier will stabilize the nodemask in a register or on - * the stack so that it will stop changing under the code. - * - * Between first_node() and next_node(), pol->nodes could be changed - * by other threads. So we put pol->nodes in a local stack. - */ - barrier(); - nnodes = nodes_weight(nodemask); + nnodes = read_once_policy_nodemask(pol, &nodemask); if (!nnodes) return numa_node_id(); target = ilx % nnodes; _ Patches currently in -mm which might be from gourry.memverge@gmail.com are mm-mempolicy-refactor-a-read-once-mechanism-into-a-function-for-re-use.patch mm-mempolicy-introduce-mpol_weighted_interleave-for-weighted-interleaving.patch mm-mempolicy-protect-task-interleave-functions-with-tsk-mems_allowed_seq.patch