linux-kernel - Re: [PATCH v4 57/66] mm/mprotect: Use maple tree navigation instead of vma linked list

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Message-ID: <c0409a4c-0cec-0b7c-594e-199ac6a787c4@suse.cz>
Date:   Thu, 20 Jan 2022 13:23:30 +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 57/66] mm/mprotect: Use maple tree navigation instead
 of vma linked list

On 12/1/21 15:30, Liam Howlett wrote:
> From: "Liam R. Howlett" <Liam.Howlett@...cle.com>
> 
> Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>

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

> ---
>  mm/mprotect.c | 7 ++++---
>  1 file changed, 4 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index e552f5e0ccbd..7af58fd467c6 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -528,6 +528,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
>  	const int grows = prot & (PROT_GROWSDOWN|PROT_GROWSUP);
>  	const bool rier = (current->personality & READ_IMPLIES_EXEC) &&
>  				(prot & PROT_READ);
> +	MA_STATE(mas, &current->mm->mm_mt, start, start);
>  
>  	start = untagged_addr(start);
>  
> @@ -559,7 +560,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
>  	if ((pkey != -1) && !mm_pkey_is_allocated(current->mm, pkey))
>  		goto out;
>  
> -	vma = find_vma(current->mm, start);
> +	vma = mas_find(&mas, ULONG_MAX);
>  	error = -ENOMEM;
>  	if (!vma)
>  		goto out;
> @@ -585,7 +586,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
>  	if (start > vma->vm_start)
>  		prev = vma;
>  	else
> -		prev = vma->vm_prev;
> +		prev = mas_prev(&mas, 0);
>  
>  	for (nstart = start ; ; ) {
>  		unsigned long mask_off_old_flags;
> @@ -647,7 +648,7 @@ static int do_mprotect_pkey(unsigned long start, size_t len,
>  		if (nstart >= end)
>  			goto out;
>  
> -		vma = prev->vm_next;
> +		vma = find_vma(current->mm, prev->vm_end);
>  		if (!vma || vma->vm_start != nstart) {
>  			error = -ENOMEM;
>  			goto out;