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Date: Mon, 15 Dec 2025 07:01:33 +0100
From: Christoph Hellwig <hch@lst.de>
To: Eric Biggers <ebiggers@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>, Jens Axboe <axboe@kernel.dk>,
	linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-fscrypt@vger.kernel.org
Subject: Re: [PATCH 7/9] blk-crypto: use mempool_alloc_bulk for encrypted
 bio page allocation
Message-ID: <20251215060133.GB31097@lst.de>
References: <20251210152343.3666103-1-hch@lst.de> <20251210152343.3666103-8-hch@lst.de> <20251213012141.GE2696@quark>
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User-Agent: Mutt/1.5.17 (2007-11-01)

On Fri, Dec 12, 2025 at 05:21:41PM -0800, Eric Biggers wrote:
> > +	memset(pages, 0, sizeof(struct page *) * nr_segs);
> > +	nr_allocated = alloc_pages_bulk(GFP_KERNEL, nr_segs, pages);
> > +	if (nr_allocated < nr_segs)
> > +		mempool_alloc_bulk(blk_crypto_bounce_page_pool, (void **)pages,
> > +				nr_segs, nr_allocated);
> 
> alloc_pages_bulk() is documented to fill in pages sequentially.  So the
> "random pages in the array unallocated" part seems misleading.  This
> also means that only the remaining portion needs to be passed to
> mempool_alloc_bulk(), similar to blk_crypto_fallback_encrypt_endio().

I the better idea is to offset the search in mempool_alloc_bulk
based on the passed in allocated argument.  I'll prepare a patch for
that.