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Date:   Thu, 1 Apr 2021 16:07:10 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Linus Torvalds <torvalds@linux-foundation.org>
Cc:     LKML <linux-kernel@vger.kernel.org>,
        Ingo Molnar <mingo@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [GIT PULL] ftrace: Check if pages were allocated before calling
 free_pages()
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On Wed, 31 Mar 2021 11:03:21 -0700
Linus Torvalds <torvalds@linux-foundation.org> wrote:

> @@ -6231,7 +6231,8 @@ static int ftrace_process_locs(struct module *mod,
>  		if (!addr)
>  			continue;
>  
> -		if (pg->index == pg->size) {
> +		end_offset = (pg->index+1) * sizeof(pg->records[0]);
> +		if (end_offset < PAGE_SIZE << pg->order) {

I believe that needs to be:

	if (end_offset >= PAGE_SIZE << pg->order) {

But as you said, you didn't test it. I'll look to see what else needs to be
fixed.

-- Steve


>  			/* We should have allocated enough */
>  			if (WARN_ON(!pg->next))
>  				break;