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bh=ohH1185Na6KXSfmzmI23KVm4RM6mKbU8oHns1dwUWjw=; b=JvMMvT6hQsYLc0fsUVb8n53/cL 6px6ShuSbDQauCbsWpFHdWSD9TvzFhOHGnlNC9tj5PhgaDfcjYqXNhRJcSr0ppq3J80gvr9LexuRD +oZ6FM34mQublv2I/eYlGiJgqcdlo58prLr5aqeldDQ9zhPwFuVvY9SlpSf2bnuZNiNQxZeGrkEYT cuMc/5FnF7pmycKA2d822mW+82QIOux9zyjVRf2J315IcYOCA8evNK9iyDFmj+hzBTXexP/kE5lty fztLizPO9bX6oTt58lZAppkSJDOsApOIGwLNo6mpHmui2KcxiU29+Lx1lMy9wj69X66TBcsNfQFui RpLoKsOw==; Received: from loth.rohan.me.apana.org.au ([192.168.167.2]) by formenos.hmeau.com with smtp (Exim 4.96 #2 (Debian)) id 1tpzHn-0048tW-1Q; Thu, 06 Mar 2025 08:40:28 +0800 Received: by loth.rohan.me.apana.org.au (sSMTP sendmail emulation); Thu, 06 Mar 2025 08:40:27 +0800 Date: Thu, 6 Mar 2025 08:40:27 +0800 From: Herbert Xu To: Yosry Ahmed Cc: Sergey Senozhatsky , Eric Biggers , Linux Crypto Mailing List , linux-mm@kvack.org Subject: Re: [RFC PATCH 7/7] mm: zswap: Use acomp virtual address interface Message-ID: References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 0FB801C0011 X-Stat-Signature: mq6tg9yjjfj7fpkaqawh18as8yhe8qwi X-Rspam-User: X-HE-Tag: 1741221646-404683 X-HE-Meta: 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 XNLKsZIq y14YV6PP2BqwXfjUKvT6VSgtuaA9gW4OUCKcRrSJhUzxtUQzX6q46ZwstfuctB/m9e7LeGuqvT2iDlDtxdYAE43WAlpJxI91R91/0b7VaGNQk+thxAM/hMzMRUkT4ntRY3f0k2Qr1EXCMQNAm58YrgRP+6dx7uPG6wcTqlpFmKkD6Vz3jDUK8/aCtcDYHKHoh9UuVv2jbd3nknQMye/PyVaBZY0WkJ0IbuIpzoa/jrhL6TybFH0FSPJe/fAKuMWbploWCYAiaNe4P1mg= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Mar 05, 2025 at 04:25:44PM +0000, Yosry Ahmed wrote: > > Zswap is already using an SG list when calling into the crypto API. The > problem is that SGs (i.e. sg_init_one()) does not support kmap highmem > addresses. Is there a fundamental reason this can't happen, or is it > just sg_set_bug() using virt_to_page(). The whole point of SG lists is so that you don't need to kmap it until the data is actually accessed. Putting kmapped memory into the SG lists defeats the purpose. > Also, since the crypto API is using SG lists internally as far as I can > tell, how does acomp_request_set_nondma() essentially deal with this? I > don't understand why we need to use a separate nondma API for highmem. I will post another acomp update soon where the hardware offload path (the only one that can't deal with nondma) will simply fall back to software compression if it sees a nondma address. Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt