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From: Matthew Wilcox <willy@infradead.org>
To: Nhat Pham <nphamcs@gmail.com>
Cc: akpm@linux-foundation.org, hannes@cmpxchg.org,
	yosryahmed@google.com, yosry.ahmed@linux.dev,
	chengming.zhou@linux.dev, linux-mm@kvack.org,
	kernel-team@meta.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v4] page_io: zswap: do not crash the kernel on decompression failure
Date: Mon, 12 May 2025 20:03:11 +0100	[thread overview]
Message-ID: <aCJF74ILruXJOAkQ@casper.infradead.org> (raw)
In-Reply-To: <20250306205011.784787-1-nphamcs@gmail.com>

On Thu, Mar 06, 2025 at 12:50:10PM -0800, Nhat Pham wrote:
> -static void zswap_decompress(struct zswap_entry *entry, struct folio *folio)
> +static bool zswap_decompress(struct zswap_entry *entry, struct folio *folio)

Hm, why do it this way?  I had it as:

-static void zswap_decompress(struct zswap_entry *entry, struct folio *folio)
+static int zswap_decompress(struct zswap_entry *entry, struct folio *folio)
...
+       err = crypto_acomp_decompress(acomp_ctx->req);
+       err = crypto_wait_req(err, &acomp_ctx->wait);
+       if (!err && acomp_ctx->req->dlen != PAGE_SIZE)
+               err = -EIO;

which allows us to return something more meaningful than -EIO.  Or is
doing that a bad idea and we should squash all decompression failures
to EIO?

(also i really dislike the chained approach:

        decomp_ret = crypto_wait_req(crypto_acomp_decompress(acomp_ctx->req), &acomp_ctx->wait);

that's much harder to understand than the two lines i have above)


  parent reply	other threads:[~2025-05-12 19:03 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-03-06 20:50 Nhat Pham
2025-03-06 21:32 ` Yosry Ahmed
2025-03-06 22:08   ` Nhat Pham
2025-03-06 22:24 ` [PATCH v4] page_io: zswap: do not crash the kernel on decompression failure (fix) Nhat Pham
2025-03-07  1:35 ` [PATCH v4] page_io: zswap: do not crash the kernel on decompression failure Johannes Weiner
2025-03-07  3:06 ` Chengming Zhou
2025-05-12 19:03 ` Matthew Wilcox [this message]
2025-05-12 19:49   ` Nhat Pham
2025-05-12 20:42     ` Matthew Wilcox

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