From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 00D5310A34 for ; Sat, 9 Mar 2024 04:38:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709959130; cv=none; b=XIGu+gMspMIFMs4s1GxTCfIYNgj6RLwVd85rHY5GiNcwQwu3n4XT3zxLYmzTWInematYInleOgqGELtdlVZR53RzaH1/piliccf6kftSCQeWjDgOg7KQWw6ghYfxAGhCcPmkHOYIKd1WLJo/kRLEy6FgMjU3AbcrdRbF01XM0Sw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1709959130; c=relaxed/simple; bh=2FN3VRj/O2qJW01n+MA08fE9SUkPhGeWx9porj64/Vc=; h=Date:To:From:Subject:Message-Id; b=BAsf3TqBGIBA2B0pavPoSw6wg6t5WoZRLuyrw+ItOFILGuIXd2REs90pA49s5aG3Hf+IOHxHJ+aSM+ngi4dNNMANhrSOOLRASioQfIVBqFpZ0I/i81inWcYYLgyq0kA5ypBXq0suwIJFg4t5KYZk8+xjRigdoEtUQAU/3p3yYkw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=0j9HvyGG; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="0j9HvyGG" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B89F8C433C7; Sat, 9 Mar 2024 04:38:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1709959129; bh=2FN3VRj/O2qJW01n+MA08fE9SUkPhGeWx9porj64/Vc=; h=Date:To:From:Subject:From; b=0j9HvyGG786IWszMjkkx+Z/9aB9Cp/o1nJRPhurl7N/LvUCt/jYZK8VFeF6RH2Kw0 8bB1XOVAImC99MEpI2wUe91Auayep8bcQbcWARFc+ypgUOxnE8Sapi3T9VXKaMgWSa N1L27pw8MJkQ4XwLLSjiLj5bBD8OLHjWdVFUgPyQ= Date: Fri, 08 Mar 2024 20:38:49 -0800 To: mm-commits@vger.kernel.org,zhouchengming@bytedance.com,yosryahmed@google.com,vitaly.wool@konsulko.com,sjenning@redhat.com,nphamcs@gmail.com,herbert@gondor.apana.org.au,hannes@cmpxchg.org,ddstreet@ieee.org,davem@davemloft.net,chrisl@kernel.org,v-songbaohua@oppo.com,akpm@linux-foundation.org From: Andrew Morton Subject: + mm-zswap-remove-the-memcpy-if-acomp-is-not-sleepable.patch added to mm-unstable branch Message-Id: <20240309043849.B89F8C433C7@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: mm/zswap: remove the memcpy if acomp is not sleepable has been added to the -mm mm-unstable branch. Its filename is mm-zswap-remove-the-memcpy-if-acomp-is-not-sleepable.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-zswap-remove-the-memcpy-if-acomp-is-not-sleepable.patch This patch will later appear in the mm-unstable branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next via the mm-everything branch at git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm and is updated there every 2-3 working days ------------------------------------------------------ From: Barry Song Subject: mm/zswap: remove the memcpy if acomp is not sleepable Date: Thu, 22 Feb 2024 21:11:35 +1300 Most compressors are actually CPU-based and won't sleep during compression and decompression. We should remove the redundant memcpy for them. This patch checks if the algorithm is sleepable by testing the CRYPTO_ALG_ASYNC algorithm flag. Generally speaking, async and sleepable are semantically similar but not equal. But for compress drivers, they are basically equal at least due to the below facts. Firstly, scompress drivers - crypto/deflate.c, lz4.c, zstd.c, lzo.c etc have no sleep. Secondly, zRAM has been using these scompress drivers for years in atomic contexts, and never worried those drivers going to sleep. One exception is that an async driver can sometimes still return synchronously per Herbert's clarification. In this case, we are still having a redundant memcpy. But we can't know if one particular acomp request will sleep or not unless crypto can expose more details for each specific request from offload drivers. Link: https://lkml.kernel.org/r/20240222081135.173040-3-21cnbao@gmail.com Signed-off-by: Barry Song Tested-by: Chengming Zhou Reviewed-by: Nhat Pham Acked-by: Yosry Ahmed Reviewed-by: Chengming Zhou Acked-by: Chris Li Acked-by: Johannes Weiner Cc: Dan Streetman Cc: David S. Miller Cc: Herbert Xu Cc: Seth Jennings Cc: Vitaly Wool Signed-off-by: Andrew Morton --- mm/zswap.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) --- a/mm/zswap.c~mm-zswap-remove-the-memcpy-if-acomp-is-not-sleepable +++ a/mm/zswap.c @@ -162,6 +162,7 @@ struct crypto_acomp_ctx { struct crypto_wait wait; u8 *buffer; struct mutex mutex; + bool is_sleepable; }; /* @@ -951,6 +952,7 @@ static int zswap_cpu_comp_prepare(unsign goto acomp_fail; } acomp_ctx->acomp = acomp; + acomp_ctx->is_sleepable = acomp_is_async(acomp); req = acomp_request_alloc(acomp_ctx->acomp); if (!req) { @@ -1078,7 +1080,7 @@ static void zswap_decompress(struct zswa mutex_lock(&acomp_ctx->mutex); src = zpool_map_handle(zpool, entry->handle, ZPOOL_MM_RO); - if (!zpool_can_sleep_mapped(zpool)) { + if (acomp_ctx->is_sleepable && !zpool_can_sleep_mapped(zpool)) { memcpy(acomp_ctx->buffer, src, entry->length); src = acomp_ctx->buffer; zpool_unmap_handle(zpool, entry->handle); @@ -1092,7 +1094,7 @@ static void zswap_decompress(struct zswa BUG_ON(acomp_ctx->req->dlen != PAGE_SIZE); mutex_unlock(&acomp_ctx->mutex); - if (zpool_can_sleep_mapped(zpool)) + if (!acomp_ctx->is_sleepable || zpool_can_sleep_mapped(zpool)) zpool_unmap_handle(zpool, entry->handle); } _ Patches currently in -mm which might be from v-songbaohua@oppo.com are mm-prohibit-the-last-subpage-from-reusing-the-entire-large-folio.patch mm-zswap-remove-the-memcpy-if-acomp-is-not-sleepable.patch