From patchwork Wed Aug 23 13:13:47 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexandru Elisei X-Patchwork-Id: 13362401 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9BFC1EE49B0 for ; Wed, 23 Aug 2023 13:19:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=8JCVQorvYt6Y/a0tnmTuBTl911DV8sKv5iPluDC/hO4=; b=od2UAwQmCA5VUK 2k8fWw8sgWuPzJ2lEO9UIsL9l7o/dMBHp/IqUWymVhQVawFRkJVJ9h0d0OugrGZLfB4zUrZVr1dcc fNE2u06VCeU5bmFfPNMo41fOQVPoQsLtQnbODxff64GsLdehUrCLvMARnvbzXPxb4waLHcMPD3epz wT3p638KRUCNDhCpSMSgvpSGVhEp8DJd/NHLEfjqP6bAQJwc+GNEHd3lcUNF1QcR7O8uV0AK3CXdv q9LHrASS3VCcsNWddCWqafrbp43pk23zhOhWaxNNz1TZF2xTeYJui3+5KZifIqqofmt7u11GAV/Ck N/AGg5ofUGhJ8NWhCPiw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qYnkj-000eob-25; Wed, 23 Aug 2023 13:18:29 +0000 Received: from foss.arm.com ([217.140.110.172]) by bombadil.infradead.org with esmtp (Exim 4.96 #2 (Red Hat Linux)) id 1qYnk6-000eTJ-2V for linux-arm-kernel@lists.infradead.org; Wed, 23 Aug 2023 13:17:52 +0000 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 6AF6E16F8; Wed, 23 Aug 2023 06:18:30 -0700 (PDT) Received: from e121798.cable.virginm.net (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 2CE8A3F740; Wed, 23 Aug 2023 06:17:44 -0700 (PDT) From: Alexandru Elisei To: catalin.marinas@arm.com, will@kernel.org, oliver.upton@linux.dev, maz@kernel.org, james.morse@arm.com, suzuki.poulose@arm.com, yuzenghui@huawei.com, arnd@arndb.de, akpm@linux-foundation.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, mhiramat@kernel.org, rppt@kernel.org, hughd@google.com Cc: pcc@google.com, steven.price@arm.com, anshuman.khandual@arm.com, vincenzo.frascino@arm.com, david@redhat.com, eugenis@google.com, kcc@google.com, hyesoo.yu@samsung.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, kvmarm@lists.linux.dev, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-mm@kvack.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH RFC 34/37] arm64: mte: Handle fatal signal in reserve_metadata_storage() Date: Wed, 23 Aug 2023 14:13:47 +0100 Message-Id: <20230823131350.114942-35-alexandru.elisei@arm.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20230823131350.114942-1-alexandru.elisei@arm.com> References: <20230823131350.114942-1-alexandru.elisei@arm.com> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20230823_061750_909738_FEABDA5D X-CRM114-Status: GOOD ( 14.10 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org As long as a fatal signal is pending, alloc_contig_range() will fail with -EINTR. This makes it impossible for tag storage allocation to succeed, and the page allocator will print an OOM splat. The process is going to be killed, so return 0 (success) from reserve_metadata_storage() to allow the page allocator to make progress. set_pte_at() will map it with PAGE_METADATA_NONE and subsequent accesses from different threads will trap until the signal is delivered. Signed-off-by: Alexandru Elisei --- arch/arm64/kernel/mte_tag_storage.c | 17 +++++++++++++++++ arch/arm64/mm/fault.c | 23 +++++++++++++++++++++++ 2 files changed, 40 insertions(+) diff --git a/arch/arm64/kernel/mte_tag_storage.c b/arch/arm64/kernel/mte_tag_storage.c index ce378f45f866..1ccbcc144979 100644 --- a/arch/arm64/kernel/mte_tag_storage.c +++ b/arch/arm64/kernel/mte_tag_storage.c @@ -556,6 +556,23 @@ int reserve_metadata_storage(struct page *page, int order, gfp_t gfp) break; } + /* + * alloc_contig_range() returns -EINTR from + * __alloc_contig_migrate_range() if a fatal signal is pending. + * As long as the signal hasn't been handled, it is impossible + * to reserve tag storage for any page. Treat it as an error, + * but return 0 so the page allocator can make forward progress, + * instead of printing an OOM splat. + * + * The tagged page with missing tag storage will be mapped with + * PAGE_METADATA_NONE in set_pte_at(), and accesses until the + * signal is delivered will cause a fault. + */ + if (ret == -EINTR) { + ret = 0; + goto out_error; + } + if (ret) goto out_error; diff --git a/arch/arm64/mm/fault.c b/arch/arm64/mm/fault.c index 7e2dcf5e3baf..64c5d77664c8 100644 --- a/arch/arm64/mm/fault.c +++ b/arch/arm64/mm/fault.c @@ -37,7 +37,9 @@ #include #include #include +#include #include +#include #include #include #include @@ -936,10 +938,31 @@ void do_debug_exception(unsigned long addr_if_watchpoint, unsigned long esr, } NOKPROBE_SYMBOL(do_debug_exception); +static void save_zero_page_tags(struct page *page) +{ + void *tags; + + clear_page(page_address(page)); + + tags = kmalloc(MTE_PAGE_TAG_STORAGE_SIZE, GFP_KERNEL | __GFP_ZERO); + if (WARN_ON(!tags)) + return; + + if (WARN_ON(mte_save_page_tags_by_pfn(page, tags))) + mte_free_tags_mem(tags); +} + void tag_clear_highpage(struct page *page) { /* Tag storage pages cannot be tagged. */ WARN_ON_ONCE(is_migrate_metadata_page(page)); + + if (metadata_storage_enabled() && + unlikely(!page_tag_storage_reserved(page))) { + save_zero_page_tags(page); + return; + } + /* Newly allocated page, shouldn't have been tagged yet */ WARN_ON_ONCE(!try_page_mte_tagging(page)); mte_zero_clear_page_tags(page_address(page));