linux-kernel - Re: [PATCH v2 tip/perf/core 4/5] uprobes: simplify find_active_uprobe

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Message-ID: <20241002062248.GA27552@redhat.com>
Date: Wed, 2 Oct 2024 08:22:49 +0200
From: Oleg Nesterov <oleg@...hat.com>
To: Andrii Nakryiko <andrii@...nel.org>
Cc: linux-trace-kernel@...r.kernel.org, peterz@...radead.org,
	rostedt@...dmis.org, mhiramat@...nel.org, bpf@...r.kernel.org,
	linux-kernel@...r.kernel.org, jolsa@...nel.org, paulmck@...nel.org,
	willy@...radead.org, surenb@...gle.com, akpm@...ux-foundation.org,
	linux-mm@...ck.org, mjguzik@...il.com, brauner@...nel.org,
	jannh@...gle.com, mhocko@...nel.org, vbabka@...e.cz,
	mingo@...nel.org
Subject: Re: [PATCH v2 tip/perf/core 4/5] uprobes: simplify
 find_active_uprobe_rcu() VMA checks

On 10/01, Andrii Nakryiko wrote:
>
> At the point where find_active_uprobe_rcu() is used we know that VMA in
> question has triggered software breakpoint, so we don't need to validate
> vma->vm_flags. Keep only vma->vm_file NULL check.
> 
> Suggested-by: Oleg Nesterov <oleg@...hat.com>
> Signed-off-by: Andrii Nakryiko <andrii@...nel.org>
> ---
>  kernel/events/uprobes.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)

Acked-by: Oleg Nesterov <oleg@...hat.com>


> diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
> index a2e6a57f79f2..7bd9111b4e8b 100644
> --- a/kernel/events/uprobes.c
> +++ b/kernel/events/uprobes.c
> @@ -2091,7 +2091,7 @@ static struct uprobe *find_active_uprobe_rcu(unsigned long bp_vaddr, int *is_swb
>  	mmap_read_lock(mm);
>  	vma = vma_lookup(mm, bp_vaddr);
>  	if (vma) {
> -		if (valid_vma(vma, false)) {
> +		if (vma->vm_file) {
>  			struct inode *inode = file_inode(vma->vm_file);
>  			loff_t offset = vaddr_to_offset(vma, bp_vaddr);
>  
> -- 
> 2.43.5
>