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Date:   Thu, 21 Jan 2021 00:12:47 +0000
From:   Matthew Wilcox <willy@infradead.org>
To:     Mike Rapoport <rppt@kernel.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Alexander Viro <viro@zeniv.linux.org.uk>,
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Subject: Re: [PATCH v15 07/11] secretmem: use PMD-size pages to amortize
 direct map fragmentation
Message-ID: <20210121001247.GN2260413@casper.infradead.org>
References: <20210120180612.1058-1-rppt@kernel.org>
 <20210120180612.1058-8-rppt@kernel.org>
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On Wed, Jan 20, 2021 at 08:06:08PM +0200, Mike Rapoport wrote:
> +static int secretmem_pool_increase(struct secretmem_ctx *ctx, gfp_t gfp)
>  {
> +	unsigned long nr_pages = (1 << PMD_PAGE_ORDER);
> +	struct gen_pool *pool = ctx->pool;
> +	unsigned long addr;
> +	struct page *page;
> +	int err;
> +
> +	page = cma_alloc(secretmem_cma, nr_pages, PMD_SIZE, gfp & __GFP_NOWARN);
> +	if (!page)
> +		return -ENOMEM;

Does cma_alloc() zero the pages it allocates?  If not, where do we avoid
leaking kernel memory to userspace?