From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 39F52C4321E for ; Mon, 28 Nov 2022 21:39:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233027AbiK1Vjv (ORCPT ); Mon, 28 Nov 2022 16:39:51 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36506 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234228AbiK1Vju (ORCPT ); Mon, 28 Nov 2022 16:39:50 -0500 Received: from sin.source.kernel.org (sin.source.kernel.org [145.40.73.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7E1712B618 for ; Mon, 28 Nov 2022 13:39:49 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by sin.source.kernel.org (Postfix) with ESMTPS id DEDCDCE1085 for ; Mon, 28 Nov 2022 21:39:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CD6EBC433D7; Mon, 28 Nov 2022 21:39:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1669671585; bh=Wl9jeM1pbDdr04CeJ15FZPczqwN26eNH5dzq24l6zs8=; h=Date:To:From:Subject:From; b=zg8z2KVixKtQcbGZ5FQdZwho9wSEH76QHECBa/vlzbEWob7HPD9XEO1pe8yaDlSB/ 3k6MXx0nupX49RFkTpo+XGvCYVcT3S1QQALMlLtxgkepd4JsXySepRGETlKhILN2Zo H0qrRh4J4Jtu9Jesl/DRXlZDmoEFIMFmbMtlxptQ= Date: Mon, 28 Nov 2022 13:39:44 -0800 To: mm-commits@vger.kernel.org, vitaly.wool@konsulko.com, sjenning@redhat.com, senozhatsky@chromium.org, nphamcs@gmail.com, ngupta@vflare.org, minchan@kernel.org, ddstreet@ieee.org, hannes@cmpxchg.org, akpm@linux-foundation.org From: Andrew Morton Subject: + zswap-fix-writeback-lock-ordering-for-zsmalloc.patch added to mm-unstable branch Message-Id: <20221128213945.CD6EBC433D7@smtp.kernel.org> Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org The patch titled Subject: zswap: fix writeback lock ordering for zsmalloc has been added to the -mm mm-unstable branch. Its filename is zswap-fix-writeback-lock-ordering-for-zsmalloc.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zswap-fix-writeback-lock-ordering-for-zsmalloc.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: Johannes Weiner Subject: zswap: fix writeback lock ordering for zsmalloc Date: Mon, 28 Nov 2022 11:16:10 -0800 Patch series "Implement writeback for zsmalloc", v7. Unlike other zswap allocators such as zbud or z3fold, zsmalloc currently lacks the writeback mechanism. This means that when the zswap pool is full, it will simply reject further allocations, and the pages will be written directly to swap. This series of patches implements writeback for zsmalloc. When the zswap pool becomes full, zsmalloc will attempt to evict all the compressed objects in the least-recently used zspages. This patch (of 6): zswap's customary lock order is tree->lock before pool->lock, because the tree->lock protects the entries' refcount, and the free callbacks in the backends acquire their respective pool locks to dispatch the backing object. zsmalloc's map callback takes the pool lock, so zswap must not grab the tree->lock while a handle is mapped. This currently only happens during writeback, which isn't implemented for zsmalloc. In preparation for it, move the tree->lock section out of the mapped entry section Link: https://lkml.kernel.org/r/20221128191616.1261026-1-nphamcs@gmail.com Link: https://lkml.kernel.org/r/20221128191616.1261026-2-nphamcs@gmail.com Signed-off-by: Johannes Weiner Signed-off-by: Nhat Pham Cc: Dan Streetman Cc: Minchan Kim Cc: Nitin Gupta Cc: Sergey Senozhatsky Cc: Seth Jennings Cc: Vitaly Wool Signed-off-by: Andrew Morton --- mm/zswap.c | 35 +++++++++++++++++++---------------- 1 file changed, 19 insertions(+), 16 deletions(-) --- a/mm/zswap.c~zswap-fix-writeback-lock-ordering-for-zsmalloc +++ a/mm/zswap.c @@ -968,6 +968,7 @@ static int zswap_writeback_entry(struct swpentry = zhdr->swpentry; /* here */ tree = zswap_trees[swp_type(swpentry)]; offset = swp_offset(swpentry); + zpool_unmap_handle(pool, handle); /* find and ref zswap entry */ spin_lock(&tree->lock); @@ -975,20 +976,12 @@ static int zswap_writeback_entry(struct if (!entry) { /* entry was invalidated */ spin_unlock(&tree->lock); - zpool_unmap_handle(pool, handle); kfree(tmp); return 0; } spin_unlock(&tree->lock); BUG_ON(offset != entry->offset); - src = (u8 *)zhdr + sizeof(struct zswap_header); - if (!zpool_can_sleep_mapped(pool)) { - memcpy(tmp, src, entry->length); - src = tmp; - zpool_unmap_handle(pool, handle); - } - /* try to allocate swap cache page */ switch (zswap_get_swap_cache_page(swpentry, &page)) { case ZSWAP_SWAPCACHE_FAIL: /* no memory or invalidate happened */ @@ -1006,6 +999,14 @@ static int zswap_writeback_entry(struct acomp_ctx = raw_cpu_ptr(entry->pool->acomp_ctx); dlen = PAGE_SIZE; + zhdr = zpool_map_handle(pool, handle, ZPOOL_MM_RO); + src = (u8 *)zhdr + sizeof(struct zswap_header); + if (!zpool_can_sleep_mapped(pool)) { + memcpy(tmp, src, entry->length); + src = tmp; + zpool_unmap_handle(pool, handle); + } + mutex_lock(acomp_ctx->mutex); sg_init_one(&input, src, entry->length); sg_init_table(&output, 1); @@ -1015,6 +1016,11 @@ static int zswap_writeback_entry(struct dlen = acomp_ctx->req->dlen; mutex_unlock(acomp_ctx->mutex); + if (!zpool_can_sleep_mapped(pool)) + kfree(tmp); + else + zpool_unmap_handle(pool, handle); + BUG_ON(ret); BUG_ON(dlen != PAGE_SIZE); @@ -1045,7 +1051,11 @@ static int zswap_writeback_entry(struct zswap_entry_put(tree, entry); spin_unlock(&tree->lock); - goto end; + return ret; + +fail: + if (!zpool_can_sleep_mapped(pool)) + kfree(tmp); /* * if we get here due to ZSWAP_SWAPCACHE_EXIST @@ -1054,17 +1064,10 @@ static int zswap_writeback_entry(struct * if we free the entry in the following put * it is also okay to return !0 */ -fail: spin_lock(&tree->lock); zswap_entry_put(tree, entry); spin_unlock(&tree->lock); -end: - if (zpool_can_sleep_mapped(pool)) - zpool_unmap_handle(pool, handle); - else - kfree(tmp); - return ret; } _ Patches currently in -mm which might be from hannes@cmpxchg.org are mm-vmscan-split-khugepaged-stats-from-direct-reclaim-stats.patch zswap-fix-writeback-lock-ordering-for-zsmalloc.patch zpool-clean-out-dead-code.patch