From nobody Sun Feb 8 20:36:46 2026 Received: from mail-pl1-f202.google.com (mail-pl1-f202.google.com [209.85.214.202]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 74E5226FD87 for ; Wed, 4 Jun 2025 23:12:29 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.202 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749078750; cv=none; b=J+Bd5hDo6BW7U1Xj7xCgLtZxAOAu3nDiprzSdWm5qcz4wuUPs3iqyBDObGiL2Ptd9QQJi/MA+kGDp1o/dDOGDrEaXBvC2Z9rYD2EyPU8yVd4AtAbZ88lWiJ2I7C9I19jdSZ232EqU706kKZykT2lHljFFAg/BOgiv8kLYUqA2Co= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1749078750; c=relaxed/simple; bh=1JKj07CL69YetOd3eAJtrIP/4dLtscsRaKvQHy9XVnU=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=WK9F9JVw1/TA9uFw0nqIF1wH5j/s/zhxB24omznqdhspiag+os/oGpo/uojsUl7ZfR2BAcRad93j5elsy23nuYvTniA7RCBI2tH+euuLYYUFy3wBpm/nfNkLJpHaib5zv7VwbV1dx5dv9c9tdOeogBDMD0eSF90704OvbeVJHnY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--surenb.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=TJVzIoT7; arc=none smtp.client-ip=209.85.214.202 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--surenb.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="TJVzIoT7" Received: by mail-pl1-f202.google.com with SMTP id d9443c01a7336-22aa75e6653so2373365ad.0 for ; Wed, 04 Jun 2025 16:12:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1749078749; x=1749683549; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=5S3jZ35KMoBO4RnXYNxi81hGE/ddSIH7so+ydU69UE8=; b=TJVzIoT7pt0B4DP3NqlGSwg+ostgG6dZHP9ZCFbM08kEnoc/yLCT8ucyA5vOT69UqA fjFl/ATtuT79r9sxhVk124XfOrFtgCj3vsaazrKFARHV8xy8gkpJzOu/ejj/3SFxLNkH 2uqw2nIArev12mAI/KwDY8/Xz8hFN6J8fY2/n2MXa0+yiI7IyaOPLp3kHYbrYXikpc/+ ogPP1HBxI43rS9SvkfueoI2VBftoRrrK4yMnvAZZChy0ML05Eh9ddz1VS1jCnuiYHCLK /6lw/qhFjCsrsCV79QL4q5b5xy4npLqBg3KcSGwrobupJJxbYXcCQ718vilBFuc0PGX1 CXTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1749078749; x=1749683549; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=5S3jZ35KMoBO4RnXYNxi81hGE/ddSIH7so+ydU69UE8=; b=MaIPPVhYn9rpKjMhvT5MQJFr0iWvCFCG2Et3wRRlIBhNBPzAcvq184ENnR3a+c6ftA KoE0OFqLgmqIy3mWO48NRkL7EAHMU/90Fy0PidKcZ8KVm3yJ3staoC++InOLI7zQl4ai YaSAFZQSjQzdY/M0u/+g2droisY8odkBpL4aGhFcLtbh+D9CRxVqQxwh6VKB9N5Fdu8H dDsl2Gc/pBxaRz6jwIHJUFwcF6FXhyO+JxP+CVguH0es8LmnIzK6nWl6l2VDcVEzh1Xk naw5+LRll1grrB2ICBi6/r8f2obpqmPhpNeBsSh0c13E4zNHn1szfDHpi7QMwyu6qnPQ Qwfw== X-Forwarded-Encrypted: i=1; AJvYcCWyIaXQtWTBfcizxkA/R1y0S4gkxMwWirsuPlgwF87e3hojXwkI82RC4y5kkPnd6KWrICdqY8J3M3cBack=@vger.kernel.org X-Gm-Message-State: AOJu0Yz5LKIIoZzP1z1NBdQTHDiuhgRPWdWWIHRdAEKcb+WNuZnIvByC zUMrEB3FXZheW7HsU83QXCWBbowCEDe8u5gebRRXWN19TRUy3hkfm4VnnY9Bp9xCZi4XceyQUsu X2xF+kA== X-Google-Smtp-Source: AGHT+IGoGwd/Y8vsxaXkZq3lcq5gV0uAcPoWJqxGcCejiu9rQZwPdtbf9qfiVIzoSAsbfmD8Xw6SbN6aqVM= X-Received: from plnz4.prod.google.com ([2002:a17:902:8344:b0:231:e2fb:ebf]) (user=surenb job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:ccd0:b0:234:e655:a62e with SMTP id d9443c01a7336-235e101356bmr63542455ad.9.1749078748733; Wed, 04 Jun 2025 16:12:28 -0700 (PDT) Date: Wed, 4 Jun 2025 16:11:51 -0700 In-Reply-To: <20250604231151.799834-1-surenb@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250604231151.799834-1-surenb@google.com> X-Mailer: git-send-email 2.49.0.1266.g31b7d2e469-goog Message-ID: <20250604231151.799834-8-surenb@google.com> Subject: [PATCH v4 7/7] mm/maps: execute PROCMAP_QUERY ioctl under per-vma locks From: Suren Baghdasaryan To: akpm@linux-foundation.org Cc: Liam.Howlett@oracle.com, lorenzo.stoakes@oracle.com, david@redhat.com, vbabka@suse.cz, peterx@redhat.com, jannh@google.com, hannes@cmpxchg.org, mhocko@kernel.org, paulmck@kernel.org, shuah@kernel.org, adobriyan@gmail.com, brauner@kernel.org, josef@toxicpanda.com, yebin10@huawei.com, linux@weissschuh.net, willy@infradead.org, osalvador@suse.de, andrii@kernel.org, ryan.roberts@arm.com, christophe.leroy@csgroup.eu, tjmercier@google.com, kaleshsingh@google.com, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kselftest@vger.kernel.org, surenb@google.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Utilize per-vma locks to stabilize vma after lookup without taking mmap_lock during PROCMAP_QUERY ioctl execution. While we might take mmap_lock for reading during contention, we do that momentarily only to lock the vma. This change is designed to reduce mmap_lock contention and prevent PROCMAP_QUERY ioctl calls from blocking address space updates. Signed-off-by: Suren Baghdasaryan Acked-by: Andrii Nakryiko --- fs/proc/task_mmu.c | 56 ++++++++++++++++++++++++++++++++++++---------- 1 file changed, 44 insertions(+), 12 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 36d883c4f394..93ba35a84975 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -550,28 +550,60 @@ static int pid_maps_open(struct inode *inode, struct = file *file) PROCMAP_QUERY_VMA_FLAGS \ ) =20 -static int query_vma_setup(struct mm_struct *mm) +#ifdef CONFIG_PER_VMA_LOCK + +static int query_vma_setup(struct proc_maps_private *priv) { - return mmap_read_lock_killable(mm); + rcu_read_lock(); + priv->locked_vma =3D NULL; + priv->mmap_locked =3D false; + + return 0; } =20 -static void query_vma_teardown(struct mm_struct *mm, struct vm_area_struct= *vma) +static void query_vma_teardown(struct proc_maps_private *priv) { - mmap_read_unlock(mm); + unlock_vma(priv); + rcu_read_unlock(); +} + +static struct vm_area_struct *query_vma_find_by_addr(struct proc_maps_priv= ate *priv, + unsigned long addr) +{ + vma_iter_init(&priv->iter, priv->mm, addr); + return get_next_vma(priv, addr); +} + +#else /* CONFIG_PER_VMA_LOCK */ + +static int query_vma_setup(struct proc_maps_private *priv) +{ + return mmap_read_lock_killable(priv->mm); +} + +static void query_vma_teardown(struct proc_maps_private *priv) +{ + mmap_read_unlock(priv->mm); } =20 -static struct vm_area_struct *query_vma_find_by_addr(struct mm_struct *mm,= unsigned long addr) +static struct vm_area_struct *query_vma_find_by_addr(struct proc_maps_priv= ate *priv, + unsigned long addr) { - return find_vma(mm, addr); + return find_vma(priv->mm, addr); } =20 -static struct vm_area_struct *query_matching_vma(struct mm_struct *mm, +#endif /* CONFIG_PER_VMA_LOCK */ + +static struct vm_area_struct *query_matching_vma(struct proc_maps_private = *priv, unsigned long addr, u32 flags) { struct vm_area_struct *vma; =20 next_vma: - vma =3D query_vma_find_by_addr(mm, addr); + vma =3D query_vma_find_by_addr(priv, addr); + if (IS_ERR(vma)) + return vma; + if (!vma) goto no_vma; =20 @@ -647,13 +679,13 @@ static int do_procmap_query(struct proc_maps_private = *priv, void __user *uarg) if (!mm || !mmget_not_zero(mm)) return -ESRCH; =20 - err =3D query_vma_setup(mm); + err =3D query_vma_setup(priv); if (err) { mmput(mm); return err; } =20 - vma =3D query_matching_vma(mm, karg.query_addr, karg.query_flags); + vma =3D query_matching_vma(priv, karg.query_addr, karg.query_flags); if (IS_ERR(vma)) { err =3D PTR_ERR(vma); vma =3D NULL; @@ -738,7 +770,7 @@ static int do_procmap_query(struct proc_maps_private *p= riv, void __user *uarg) } =20 /* unlock vma or mmap_lock, and put mm_struct before copying data to user= */ - query_vma_teardown(mm, vma); + query_vma_teardown(priv); mmput(mm); =20 if (karg.vma_name_size && copy_to_user(u64_to_user_ptr(karg.vma_name_addr= ), @@ -758,7 +790,7 @@ static int do_procmap_query(struct proc_maps_private *p= riv, void __user *uarg) return 0; =20 out: - query_vma_teardown(mm, vma); + query_vma_teardown(priv); mmput(mm); kfree(name_buf); return err; --=20 2.49.0.1266.g31b7d2e469-goog