linux-kernel - Re: [PATCH v4 46/66] perf: Use VMA iterator

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Date:   Wed, 19 Jan 2022 17:47:27 +0100
From:   Vlastimil Babka <vbabka@...e.cz>
To:     Liam Howlett <liam.howlett@...cle.com>,
        "maple-tree@...ts.infradead.org" <maple-tree@...ts.infradead.org>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Cc:     Song Liu <songliubraving@...com>,
        Davidlohr Bueso <dave@...olabs.net>,
        "Paul E . McKenney" <paulmck@...nel.org>,
        Matthew Wilcox <willy@...radead.org>,
        Laurent Dufour <ldufour@...ux.ibm.com>,
        David Rientjes <rientjes@...gle.com>,
        Axel Rasmussen <axelrasmussen@...gle.com>,
        Suren Baghdasaryan <surenb@...gle.com>,
        Rik van Riel <riel@...riel.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Michel Lespinasse <walken.cr@...il.com>,
        Jerome Glisse <jglisse@...hat.com>,
        Minchan Kim <minchan@...gle.com>,
        Joel Fernandes <joelaf@...gle.com>,
        Rom Lemarchand <romlem@...gle.com>
Subject: Re: [PATCH v4 46/66] perf: Use VMA iterator

On 12/1/21 15:30, Liam Howlett wrote:
> From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
> 
> The VMA iterator is faster than the linked list and removing the linked
> list will shrink the vm_area_struct.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@...radead.org>
> Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>

Acked-by: Vlastimil Babka <vbabka@...e.cz>

> ---
>  kernel/events/core.c    | 3 ++-
>  kernel/events/uprobes.c | 9 ++++++---
>  2 files changed, 8 insertions(+), 4 deletions(-)
> 
> diff --git a/kernel/events/core.c b/kernel/events/core.c
> index 523106a506ee..d839ba79fe5c 100644
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -10218,8 +10218,9 @@ static void perf_addr_filter_apply(struct perf_addr_filter *filter,
>  				   struct perf_addr_filter_range *fr)
>  {
>  	struct vm_area_struct *vma;
> +	VMA_ITERATOR(vmi, mm, 0);
>  
> -	for (vma = mm->mmap; vma; vma = vma->vm_next) {
> +	for_each_vma(vmi, vma) {
>  		if (!vma->vm_file)
>  			continue;
>  
> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index 6357c3580d07..5dee6c41f36d 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -356,9 +356,10 @@ static bool valid_ref_ctr_vma(struct uprobe *uprobe,
>  static struct vm_area_struct *
>  find_ref_ctr_vma(struct uprobe *uprobe, struct mm_struct *mm)
>  {
> +	VMA_ITERATOR(vmi, mm, 0);
>  	struct vm_area_struct *tmp;
>  
> -	for (tmp = mm->mmap; tmp; tmp = tmp->vm_next)
> +	for_each_vma(vmi, tmp)
>  		if (valid_ref_ctr_vma(uprobe, tmp))
>  			return tmp;
>  
> @@ -1237,11 +1238,12 @@ int uprobe_apply(struct inode *inode, loff_t offset,
>  
>  static int unapply_uprobe(struct uprobe *uprobe, struct mm_struct *mm)
>  {
> +	VMA_ITERATOR(vmi, mm, 0);
>  	struct vm_area_struct *vma;
>  	int err = 0;
>  
>  	mmap_read_lock(mm);
> -	for (vma = mm->mmap; vma; vma = vma->vm_next) {
> +	for_each_vma(vmi, vma) {
>  		unsigned long vaddr;
>  		loff_t offset;
>  
> @@ -1989,9 +1991,10 @@ bool uprobe_deny_signal(void)
>  
>  static void mmf_recalc_uprobes(struct mm_struct *mm)
>  {
> +	VMA_ITERATOR(vmi, mm, 0);
>  	struct vm_area_struct *vma;
>  
> -	for (vma = mm->mmap; vma; vma = vma->vm_next) {
> +	for_each_vma(vmi, vma) {
>  		if (!valid_vma(vma, false))
>  			continue;
>  		/*