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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 6E329C44536 for ; Wed, 22 Jul 2026 15:21:41 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 736316B00B9; Wed, 22 Jul 2026 11:21:40 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 70D5D6B00BA; Wed, 22 Jul 2026 11:21:40 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 5FDC36B00BB; Wed, 22 Jul 2026 11:21:40 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0016.hostedemail.com [216.40.44.16]) by kanga.kvack.org (Postfix) with ESMTP id 3C6106B00B9 for ; Wed, 22 Jul 2026 11:21:40 -0400 (EDT) Received: from smtpin29.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay08.hostedemail.com (Postfix) with ESMTP id BEF79140201 for ; Wed, 22 Jul 2026 15:21:39 +0000 (UTC) X-FDA: 85016777118.29.4029721 Received: from out-177.mta1.migadu.com (out-177.mta1.migadu.com [95.215.58.177]) by imf30.hostedemail.com (Postfix) with ESMTP id DE7CF80010 for ; Wed, 22 Jul 2026 15:21:37 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=PpjeU8Ai; spf=pass (imf30.hostedemail.com: domain of usama.arif@linux.dev designates 95.215.58.177 as permitted sender) smtp.mailfrom=usama.arif@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1784733698; b=trsNudlP9umSGbXCPn9PcMvQN8vqMtNaeh0/ohYuNI/b0sLT+bz57nTQE/95skfxIWKJmY YjSyfkjwdY64UzPPmxWgY5qjN0U21oe+T4TEgISs9P1bUJhmqISJmaVSat0PJDrgQ7y4dF AKQUSippEHbfAePAQhpq8S6lvWLwOQc= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=linux.dev header.s=key1 header.b=PpjeU8Ai; spf=pass (imf30.hostedemail.com: domain of usama.arif@linux.dev designates 95.215.58.177 as permitted sender) smtp.mailfrom=usama.arif@linux.dev; dmarc=pass (policy=none) header.from=linux.dev ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1784733698; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=DewUAhzakWqHnF6VoxFjXFO25R073z6cEiSODUJgVTA=; b=wt7BM5lk5XSlbNywoCYOZ061TxBb34ZzPz0JyBpuyUG1YwuPcigbOpaUsTi6QE47KPH/gQ 7lT0ZrPnnMv1NDJZX5+BO9jYefX957IvNXvy/n2jI7LqjGFwdqGZEvhf//hNKVkldStIK0 Ie490oYtdHZGxR+Ee+LQM5RKJjGez2E= X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1784733696; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=DewUAhzakWqHnF6VoxFjXFO25R073z6cEiSODUJgVTA=; b=PpjeU8Ai7QJ+j1EQvdHgQBe60U5pDk1ClQ/f2mPV3ZHtKz1TlDO62fS/QgP2cBQBpxOQ/B 19fHPYsVhaCn5QG2FvxAnuz/O9YJ0QY9YYpDyK2NDJHp6zGakyY7aOWLpMCIBcnGqfxhta geGN+XadjJNItwGxKgrm6BXVwYeizaU= From: Usama Arif To: Andrew Morton , david@kernel.org, chrisl@kernel.org, kasong@tencent.com, ljs@kernel.org, ziy@nvidia.com, linux-mm@kvack.org Cc: ying.huang@linux.alibaba.com, Baoquan He , willy@infradead.org, youngjun.park@lge.com, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, alex@ghiti.fr, kas@kernel.org, baohua@kernel.org, dev.jain@arm.com, baolin.wang@linux.alibaba.com, Nico Pache , Liam R. Howlett , ryan.roberts@arm.com, Vlastimil Babka , lance.yang@linux.dev, linux-kernel@vger.kernel.org, nphamcs@gmail.com, shikemeng@huaweicloud.com, yosry@kernel.org, kernel-team@meta.com, Alexandre Ghiti , Usama Arif Subject: [PATCH v5 04/11] mm: zswap: add range lookup for large-folio swapin Date: Wed, 22 Jul 2026 08:19:35 -0700 Message-ID: <20260722152043.2273289-5-usama.arif@linux.dev> In-Reply-To: <20260722152043.2273289-1-usama.arif@linux.dev> References: <20260722152043.2273289-1-usama.arif@linux.dev> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT X-Stat-Signature: 3e9sab1n5ijndt3xe77aswdx5c46hpw1 X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: DE7CF80010 X-Rspam-User: X-HE-Tag: 1784733697-721255 X-HE-Meta: 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 q8CuRht6 tRT+Z66fMSF+lqyR1zSh8Au3lGCrp8kWcENZWV8fWrHwvRuLGcAXtT5cTFUVU0K+QNq5SYb8wF1wVZ0eXt0s55Wd7A/a5WkXcDg/QB7nxBr7uC5fJjTAeWFVr15QJUw4ib+/ESzN71ZLg9Q632ZlDocusfQF1I25qpERiCVpPLKBSdjMZJlXDSg6jZt3kR/CCwidCG7ckykMaCA3BpYLbntIcZnEaHEha11ty Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: From: Alexandre Ghiti A large folio reaches zswap_load() only when the caller expects the whole range to be on disk. Zswap still stores large folios as independent order-0 entries, so reconstructing a large folio from zswap entries would risk returning partially initialized data. Teach zswap_load() to scan the covered range. If no slot is in zswap, return -ENOENT so swap_read_folio() reads the backing device. If any slot is still in zswap, fail the large-folio read so the caller can fall back to per-page swapin. Return -EIO rather than -EINVAL for that conflict. Large-folio loads are now valid requests; the error means zswap cannot safely satisfy the request from partial per-page compressed state, not that the request is unsupported. Existing callers only distinguish -ENOENT, so this is a semantic clarification rather than a behavioral change. Add zswap_is_present() so PMD swap-entry consumers can make the same range decision before attempting PMD-order swapin. Signed-off-by: Alexandre Ghiti Signed-off-by: Usama Arif --- include/linux/zswap.h | 6 ++++++ mm/zswap.c | 42 ++++++++++++++++++++++++++++++++---------- 2 files changed, 38 insertions(+), 10 deletions(-) diff --git a/include/linux/zswap.h b/include/linux/zswap.h index 30c193a1207e..cd9efcf9dec9 100644 --- a/include/linux/zswap.h +++ b/include/linux/zswap.h @@ -35,6 +35,7 @@ void zswap_lruvec_state_init(struct lruvec *lruvec); void zswap_folio_swapin(struct folio *folio); bool zswap_is_enabled(void); bool zswap_never_enabled(void); +bool zswap_is_present(swp_entry_t entry, unsigned int nr); #else struct zswap_lruvec_state {}; @@ -69,6 +70,11 @@ static inline bool zswap_never_enabled(void) return true; } +static inline bool zswap_is_present(swp_entry_t entry, unsigned int nr) +{ + return false; +} + #endif #endif /* _LINUX_ZSWAP_H */ diff --git a/mm/zswap.c b/mm/zswap.c index 4e76a4a87cdc..384492f1f696 100644 --- a/mm/zswap.c +++ b/mm/zswap.c @@ -1561,6 +1561,23 @@ bool zswap_store(struct folio *folio) return ret; } +/** + * zswap_is_present() - is any slot in [entry, entry + nr) in zswap? + * @entry: base swap entry of the range + * @nr: number of contiguous slots to check (pass 1 for a single-slot query) + */ +bool zswap_is_present(swp_entry_t entry, unsigned int nr) +{ + pgoff_t offset = swp_offset(entry); + struct xarray *tree = swap_zswap_tree(entry); + unsigned long index = offset; + + if (!nr || zswap_never_enabled()) + return false; + + return xa_find(tree, &index, offset + nr - 1, XA_PRESENT); +} + /** * zswap_load() - load a folio from zswap * @folio: folio to load @@ -1573,10 +1590,9 @@ bool zswap_store(struct folio *folio) * NOT marked up-to-date, so that an IO error is emitted (e.g. do_swap_page() * will SIGBUS). * - * -EINVAL: if the swapped out content was in zswap, but the page belongs - * to a large folio, which is not supported by zswap. The folio is unlocked, - * but NOT marked up-to-date, so that an IO error is emitted (e.g. - * do_swap_page() will SIGBUS). + * -EIO: if a slot in a large-folio range is unexpectedly still in zswap. + * The folio is unlocked, but NOT marked up-to-date, so that an IO + * error is emitted (e.g. do_swap_page() will SIGBUS). * * -ENOENT: if the swapped out content was not in zswap. The folio remains * locked on return. @@ -1595,13 +1611,19 @@ int zswap_load(struct folio *folio) return -ENOENT; /* - * Large folios should not be swapped in while zswap is being used, as - * they are not properly handled. Zswap does not properly load large - * folios, and a large folio may only be partially in zswap. + * A large folio reaches zswap_load() only when its whole range is + * expected to be on disk: PMD swap-entry consumers split before + * calling into PMD-order swapin whenever any slot is still in zswap. + * Confirm the range is entirely absent from zswap and return -ENOENT + * so the caller reads it from disk; if a slot is unexpectedly still in + * zswap, fail the read rather than return partially-initialized data. */ - if (WARN_ON_ONCE(folio_test_large(folio))) { - folio_unlock(folio); - return -EINVAL; + if (folio_test_large(folio)) { + if (zswap_is_present(swp, folio_nr_pages(folio))) { + folio_unlock(folio); + return -EIO; + } + return -ENOENT; } entry = xa_load(tree, offset); -- 2.53.0-Meta