linux-kernel - Re: [PATCH v4 6/6] mm: handle userfaults under VMA lock

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Message-ID: <ZJxkEVWMAXnz8Y9D@x1n>
Date:   Wed, 28 Jun 2023 12:47:13 -0400
From:   Peter Xu <peterx@...hat.com>
To:     Suren Baghdasaryan <surenb@...gle.com>
Cc:     akpm@...ux-foundation.org, willy@...radead.org, hannes@...xchg.org,
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Subject: Re: [PATCH v4 6/6] mm: handle userfaults under VMA lock

On Wed, Jun 28, 2023 at 09:22:24AM -0700, Suren Baghdasaryan wrote:
> Ack. I was not sure if the ctx->mm would always be the same as vmf->mm.

Feel free to look at the entrance of handle_userfault(), where there's:

	struct vm_area_struct *vma = vmf->vma;
	struct mm_struct *mm = vma->vm_mm;
	struct userfaultfd_ctx *ctx;
        ...
	ctx = vma->vm_userfaultfd_ctx.ctx;
        ...
	BUG_ON(ctx->mm != mm);
        ...

So I think we should be safe.  Thanks,

-- 
Peter Xu