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 6995C2F4A for ; Mon, 9 Jun 2025 19:35:35 +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=1749497735; cv=none; b=m90UUqH2hTP+jrn+gnpUwR1KmPkJV+FY0tn3F+mqH+KsUNJFIRd66EJmM4Q3XDgI5xP55S8BNcJayv7OdG4Djf+eJDawcyD3pwZNlWsRIeo3ly8ZiVUlyyTExHbOVavywbyz/c46d423lZVjfHHbA5acqYPFUQpetlTl5GnLWGI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749497735; c=relaxed/simple; bh=zuKeiaXX2xkkKu6ZEn4SauDBHyUGXTnlvIKb59rpBwg=; h=Date:To:From:Subject:Message-Id; b=ATTvMxqOHlcCO+f2VDEb7opSba5Emnp+v/uuboetu3c/0iVvagyE5EcK2yxUztbod56ipfVJE86zilNmT6Ni1JxYBiOIequIgQdvgvfJ6xH9dbT3sTU6JNIO6h9rfKm63k+chEhFS9qkciq2pT/fSX1c9+RqaKi1zz6XEmqPX4g= 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=w3zqeyPD; 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="w3zqeyPD" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ECE5EC4CEEB; Mon, 9 Jun 2025 19:35:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1749497735; bh=zuKeiaXX2xkkKu6ZEn4SauDBHyUGXTnlvIKb59rpBwg=; h=Date:To:From:Subject:From; b=w3zqeyPD7ouuomQSXFNVBpt2qkYxtvAuv95+vmF1s2CCGKULh0iuIpS9T/w06W4sd J2yq47vUF5K3vLaBVFT6GHBt3/iJqhGe0e3US2uv1xUEiWtAv5lSU4zJ17aZ/z4/UZ vMQrrGBQwkAm+BuaT0kRrkQ5NS17a0do4WmQN9M4= Date: Mon, 09 Jun 2025 12:35:34 -0700 To: mm-commits@vger.kernel.org,rppt@kernel.org,pasha.tatashin@soleen.com,mjguzik@gmail.com,linus.walleij@linaro.org,akpm@linux-foundation.org From: Andrew Morton Subject: + fork-define-a-local-gfp_vmap_stack.patch added to mm-nonmm-unstable branch Message-Id: <20250609193534.ECE5EC4CEEB@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: fork: define a local GFP_VMAP_STACK has been added to the -mm mm-nonmm-unstable branch. Its filename is fork-define-a-local-gfp_vmap_stack.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/fork-define-a-local-gfp_vmap_stack.patch This patch will later appear in the mm-nonmm-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: Linus Walleij Subject: fork: define a local GFP_VMAP_STACK Date: Fri, 09 May 2025 09:25:09 +0200 The current allocation of VMAP stack memory is using (THREADINFO_GFP & ~__GFP_ACCOUNT) which is a complicated way of saying (GFP_KERNEL | __GFP_ZERO): : define THREADINFO_GFP (GFP_KERNEL_ACCOUNT | __GFP_ZERO) : define GFP_KERNEL_ACCOUNT (GFP_KERNEL | __GFP_ACCOUNT) This is an unfortunate side-effect of independent changes blurring the picture: commit 19809c2da28aee5860ad9a2eff760730a0710df0 changed (THREADINFO_GFP | __GFP_HIGHMEM) to just THREADINFO_GFP since highmem became implicit. commit 9b6f7e163cd0f468d1b9696b785659d3c27c8667 then added stack caching and rewrote the allocation to (THREADINFO_GFP & ~__GFP_ACCOUNT) as cached stacks need to be accounted separately. However that code, when it eventually accounts the memory does this: ret = memcg_kmem_charge(vm->pages[i], GFP_KERNEL, 0) so the memory is charged as a GFP_KERNEL allocation. Define a unique GFP_VMAP_STACK to use GFP_KERNEL | __GFP_ZERO and move the comment there. Link: https://lkml.kernel.org/r/20250509-gfp-stack-v1-1-82f6f7efc210@linaro.org Signed-off-by: Linus Walleij Reported-by: Mateusz Guzik Cc: Pasha Tatashin Cc: Mike Rapoport (Microsoft) Signed-off-by: Andrew Morton --- kernel/fork.c | 13 +++++++------ 1 file changed, 7 insertions(+), 6 deletions(-) --- a/kernel/fork.c~fork-define-a-local-gfp_vmap_stack +++ a/kernel/fork.c @@ -201,6 +201,12 @@ static inline void free_task_struct(stru */ #define NR_CACHED_STACKS 2 static DEFINE_PER_CPU(struct vm_struct *, cached_stacks[NR_CACHED_STACKS]); +/* + * Allocated stacks are cached and later reused by new threads, so memcg + * accounting is performed by the code assigning/releasing stacks to tasks. + * We need a zeroed memory without __GFP_ACCOUNT. + */ +#define GFP_VMAP_STACK (GFP_KERNEL | __GFP_ZERO) struct vm_stack { struct rcu_head rcu; @@ -307,13 +313,8 @@ static int alloc_thread_stack_node(struc return 0; } - /* - * Allocated stacks are cached and later reused by new threads, - * so memcg accounting is performed manually on assigning/releasing - * stacks to tasks. Drop __GFP_ACCOUNT. - */ stack = __vmalloc_node(THREAD_SIZE, THREAD_ALIGN, - THREADINFO_GFP & ~__GFP_ACCOUNT, + GFP_VMAP_STACK, node, __builtin_return_address(0)); if (!stack) return -ENOMEM; _ Patches currently in -mm which might be from linus.walleij@linaro.org are fork-define-a-local-gfp_vmap_stack.patch