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]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9588DC48BF8 for ; Thu, 22 Feb 2024 10:26:32 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 16A196B007E; Thu, 22 Feb 2024 05:26:32 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 11A856B0081; Thu, 22 Feb 2024 05:26:32 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 008A56B0082; Thu, 22 Feb 2024 05:26:31 -0500 (EST) 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 E56EB6B007E for ; Thu, 22 Feb 2024 05:26:31 -0500 (EST) Received: from smtpin15.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 80E28C03CC for ; Thu, 22 Feb 2024 10:26:31 +0000 (UTC) X-FDA: 81819060582.15.3EE13F5 Received: from out-172.mta1.migadu.com (out-172.mta1.migadu.com [95.215.58.172]) by imf17.hostedemail.com (Postfix) with ESMTP id 87C224000F for ; Thu, 22 Feb 2024 10:26:28 +0000 (UTC) Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=uBIsCIa1; spf=pass (imf17.hostedemail.com: domain of yajun.deng@linux.dev designates 95.215.58.172 as permitted sender) smtp.mailfrom=yajun.deng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1708597588; 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=+7spRFbh2J4ww37DpVZh+dxZFQJF6WKI0aJByND9M2M=; b=397oKPlUhacp8gzvbcG7HcJY8c/jGlgNJOUqznF/Fg4w3CiF01Ei0c5DUeHOFC+qs+cBMo bR2RKh9s53RUKEgSjI61ZZ5pkTiwSO44cKGrUAJXOryO+9YbgEyrY8ezogyMVckNdzHmwa VxgybFJq6T5VP1Mx4N03ehBi8lfEmhU= ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1708597588; a=rsa-sha256; cv=none; b=r/aoNBNwhVXew7IeY+6lH5gwb3HRJ/pM3Bl/QbdkwxYFE0bvCTtsEsBxPIzPqrJt87mebO gTN5aiyqWj8WounHRqRMZ8y714kma48CXJPFfD70bNXP4q1B0Bp/JtcGfcaS8qYZOdxLrB mXU2HrVIDLXrgdiF1aIciRv+ZVtvwp0= ARC-Authentication-Results: i=1; imf17.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=uBIsCIa1; spf=pass (imf17.hostedemail.com: domain of yajun.deng@linux.dev designates 95.215.58.172 as permitted sender) smtp.mailfrom=yajun.deng@linux.dev; dmarc=pass (policy=none) header.from=linux.dev Message-ID: <7229eb6e-bf3e-fa97-6709-6c92bc72443b@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1708597586; h=from:from: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; bh=+7spRFbh2J4ww37DpVZh+dxZFQJF6WKI0aJByND9M2M=; b=uBIsCIa13A/Fs89WWjKMTg//DsS1q1bl0lRGY8fIonQKfUYADQPrsYRucSSGgCr1k7komW ABm8yceiEl3msvXaPyDirssN/rn0BImI/8NeKLNmo6VaDzgB3DKaQIiUomdRMsc8c5yg09 dEHQK2kIhgLQCC+P3JZ/XAFLRCgO/FA= Date: Thu, 22 Feb 2024 18:26:18 +0800 MIME-Version: 1.0 Subject: Re: [PATCH] mm/mmap: remove the mm parameter in vma_complete() Content-Language: en-US To: "Liam R. Howlett" References: <20240129075305.3512138-1-yajun.deng@linux.dev> <20240129150417.3m6jyj3ftdh6ka7x@revolver> Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, vbabka@suse.cz, lstoakes@gmail.com X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yajun Deng In-Reply-To: <20240129150417.3m6jyj3ftdh6ka7x@revolver> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: 5pew5grhrgb8gwni7stz8wsmoqygzktw X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 87C224000F X-Rspam-User: X-HE-Tag: 1708597588-577180 X-HE-Meta: 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 g6Cd53AJ W66qZVgK/9GNwMdQ26Ggbra4ZJczoWHPjaP8kKMFLM/rOJgiB7NNk8aE8G79BB9bC9KlKhgI+IwiJxj3vydxkfx5BX71tsWyakFBHCKl+TJiEj/ubBHe/orBxoIQ7sLIAiRxcMNBVklBDG84tkC7VTubZi8FmbVljCMY0 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Adding Vlastimil and Lorenzo to discuss this patch. On 2024/1/29 23:04, Liam R. Howlett wrote: > * Yajun Deng [240129 02:53]: >> There are vma_merge() and do_brk_flags() pass mm to vma_complete(), others >> would pass the vma->vm_mm. The following explains that the mm is the >> vma->vm_mm in vma_merge() and do_brk_flags(). >> >> All vma will point to the same mm struct if the vma_merge() is successful. >> So the mm and the vma->mm are the same. > Absolutely, they must be the same. I don't think vma_merge() checks > this, but it is true. > >> vm_brk_flags() and brk syscall will initialize vmi with current->mm, >> so the vma->vm_mm and the current->mm are the same if vma exists in >> do_brk_flags(). >> >> Remove the mm parameter in vma_complete() and get mm from the vma in vp. > You have added a dereference to the two paths that don't need it to > reduce the argument list from 3 to 2. It's the same number of lines as > well. vma_shrink() is only used on process creation, but brk is more > common. Note that this function is marked as inline. > > I'm not sure this change is worth making. If we can make sure the mm is  vma->vm_mm, I don't think we need to pass the mm. If we can't make sure that, this change is not worth it. >> Signed-off-by: Yajun Deng >> --- >> mm/mmap.c | 16 ++++++++-------- >> 1 file changed, 8 insertions(+), 8 deletions(-) >> >> diff --git a/mm/mmap.c b/mm/mmap.c >> index e97b9144c61a..9b968d1edf55 100644 >> --- a/mm/mmap.c >> +++ b/mm/mmap.c >> @@ -509,11 +509,11 @@ static inline void vma_prepare(struct vma_prepare *vp) >> * >> * @vp: The vma_prepare struct >> * @vmi: The vma iterator >> - * @mm: The mm_struct >> */ >> -static inline void vma_complete(struct vma_prepare *vp, >> - struct vma_iterator *vmi, struct mm_struct *mm) >> +static inline void vma_complete(struct vma_prepare *vp, struct vma_iterator *vmi) >> { >> + struct mm_struct *mm = vp->vma->vm_mm; >> + >> if (vp->file) { >> if (vp->adj_next) >> vma_interval_tree_insert(vp->adj_next, >> @@ -666,7 +666,7 @@ int vma_expand(struct vma_iterator *vmi, struct vm_area_struct *vma, >> vma_set_range(vma, start, end, pgoff); >> vma_iter_store(vmi, vma); >> >> - vma_complete(&vp, vmi, vma->vm_mm); >> + vma_complete(&vp, vmi); >> return 0; >> >> nomem: >> @@ -707,7 +707,7 @@ int vma_shrink(struct vma_iterator *vmi, struct vm_area_struct *vma, >> >> vma_iter_clear(vmi); >> vma_set_range(vma, start, end, pgoff); >> - vma_complete(&vp, vmi, vma->vm_mm); >> + vma_complete(&vp, vmi); >> return 0; >> } >> >> @@ -1030,7 +1030,7 @@ static struct vm_area_struct >> } >> } >> >> - vma_complete(&vp, vmi, mm); >> + vma_complete(&vp, vmi); >> khugepaged_enter_vma(res, vm_flags); >> return res; >> >> @@ -2377,7 +2377,7 @@ static int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma, >> } >> >> /* vma_complete stores the new vma */ >> - vma_complete(&vp, vmi, vma->vm_mm); >> + vma_complete(&vp, vmi); >> >> /* Success. */ >> if (new_below) >> @@ -3145,7 +3145,7 @@ static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma, >> vm_flags_set(vma, VM_SOFTDIRTY); >> vma_iter_store(vmi, vma); >> >> - vma_complete(&vp, vmi, mm); >> + vma_complete(&vp, vmi); >> khugepaged_enter_vma(vma, flags); >> goto out; >> } >> -- >> 2.25.1 >> >>