From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 53A27606EEA5 for ; Wed, 4 Nov 2026 17:28:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=sY65AgOu; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=WlF7tGad DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References :Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Unsubscribe-Post: List-Owner; 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Wed, 4 Nov 2026 17:28:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793813333; bh=Em8mdDwLTSxa5ZBRNu+oIoQ2F8Zgf6ZNSHVwHsLTxqQ=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=WlF7tGadWEgcoZaI1uK4E88iTTgepprrifasds75i7VthYlwDtZlbOT38njQBleEb UPbfRvu/3NbdJdmajozNFYEjQ7CLKo3CQ2J3GJ8KprOwgxaPeKR/tPjmsa1SVubVZc 1en2pZ6ZJTtEVyIRxb8Akk8hz+i5vksUw5t9jkHwoekjj/VsrPO/9oQMYE5lUZ/Gmm GUjsDpi349fDqaFLbiGR7qDbPwtf9QbhpGmf9fVBlF6p4pM0JpJvP1ofrRorpGAY+w 2xFkMHZ1ZzA18zc8/hnvV/Wnix3shLePBWHi7TeHk0dW6WQ7yqtTL3j1rmlfaIJEkz qVzdX/epmct3g== From: Christian Brauner Date: Wed, 04 Nov 2026 18:27:18 +0100 Subject: [PATCH v2 01/51] alloc_tag: don't remove /proc/allocinfo under the codetag module lock X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261104-work-procfs-bugfixes-v2-1-bbf7d5546809@kernel.org> References: <20261104-work-procfs-bugfixes-v2-0-bbf7d5546809@kernel.org> In-Reply-To: <20261104-work-procfs-bugfixes-v2-0-bbf7d5546809@kernel.org> To: linux-fsdevel@vger.kernel.org Cc: Linus Torvalds , Jann Horn , Josef Bacik , Chris Mason , Jeff Layton , NeilBrown , Eric Dumazet , Thomas Gleixner , Al Viro , Jonathan Corbet , Christoph Hellwig , Greg Kroah-Hartman , Joel Granados , Kees Cook , Jan Kara , Jan Kara , linux-kernel@vger.kernel.org, linux-nfs@vger.kernel.org, linux-acpi@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-s390@vger.kernel.org, linux-scsi@vger.kernel.org, linux-um@lists.infradead.org, linux-wireless@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, netdev@vger.kernel.org, ntfs3@lists.linux.dev, platform-driver-x86@vger.kernel.org, coreteam@netfilter.org, kexec@lists.infradead.org, linux-pci@vger.kernel.org, linux-sound@vger.kernel.org, netfilter-devel@vger.kernel.org, dri-devel@lists.freedesktop.org, ibm-acpi-devel@lists.sourceforge.net, jfs-discussion@lists.sourceforge.net, linux-alpha@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-cifs@vger.kernel.org, linux-fbdev@vger.kernel.org, linux-hwmon@vger.kernel.org, linux-mm@kvack.org, linux-sh@vger.kernel.org, linux-usb@vger.kernel.org, samba-technical@lists.samba.org, sparclinux@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-doc@vger.kernel.org, linux-serial@vger.kernel.org, linux-atm-general@lists.sourceforge.net, Takashi Iwai , linux-input@vger.kernel.org, linux-raid@vger.kernel.org, linux-ext4@vger.kernel.org, linux-modules@vger.kernel.org, linux-debuggers@vger.kernel.org, "Christian Brauner (Amutable)" , Chuck Lever , stable@vger.kernel.org X-Mailer: b4 0.17-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=3465; i=brauner@kernel.org; h=from:subject:message-id; bh=C5Mw1tWGzCvAVdyOdBCkcSqd8MeBZuRbzsUttoDJMVc=; b=owGbwMvMwCU28Zj0gdSKO4sYT6slMWS9zvplOalNaKKt8vuu2b8lsnQOcTE/KzbYPv1ll+Xp5 mmPQhjTO0pZGMS4GGTFFFkc2k3C5ZbzVGw2ytSAmcPKBDKEgYtTACaSn8/wm81Zr+lISs2Ek/OM L7KdEcq5v/O1XVLdtyWXdiY8F0/he8vwV96O52JXaCnv3ctHP3V8+3Zga6R61CzWK7HM88uSHpZ tYwQA X-Developer-Key: i=brauner@kernel.org; a=openpgp; fpr=4880B8C9BD0E5106FC070F4F7B3C391EFEA93624 X-BeenThere: linux-um@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-um" X-Spam-Status: No, score=-18.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 codetag_alloc_module_section() takes the codetag type's mod_lock for writing and calls reserve_module_tags() with it held. When that can't reserve the tags, because the section's alignment doesn't fit, because there are too many tags for the page flag bits or because the memory for them can't be allocated, it shuts memory allocation profiling down and removes /proc/allocinfo, still with mod_lock held. remove_proc_entry() waits until every reader of the entry has let go of it, and a reader of /proc/allocinfo takes mod_lock for reading in allocinfo_start() while it holds the entry. So a module load that hits one of those paths while /proc/allocinfo is being read waits for the reader and the reader waits for the module load, for good. Let a work item remove the entry in that case. The profiling is shut down right away like before, the file just goes a moment later. Fixes: 4835f747d3ed ("alloc_tag: support for page allocation tag compression") Cc: stable@vger.kernel.org Signed-off-by: Christian Brauner (Amutable) --- mm/alloc_tag.c | 27 ++++++++++++++++++++++++--- 1 file changed, 24 insertions(+), 3 deletions(-) diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c index 82e2c3448dcf..7d7ad6704953 100644 --- a/mm/alloc_tag.c +++ b/mm/alloc_tag.c @@ -15,6 +15,7 @@ #include #include #include +#include #include #include @@ -604,6 +605,26 @@ static void shutdown_mem_profiling(bool remove_file) mem_profiling_support = false; } +static void remove_allocinfo_file(struct work_struct *work) +{ + remove_proc_entry(ALLOCINFO_FILE_NAME, NULL); +} +static DECLARE_WORK(remove_allocinfo_work, remove_allocinfo_file); + +/* + * A module's tags are reserved with the codetag module lock held for + * writing, and a reader of /proc/allocinfo takes that lock with the entry + * pinned. Removing the entry there would wait for that reader for good, so + * let a work item do it. + */ +static void shutdown_mem_profiling_async(void) +{ + if (!mem_profiling_support) + return; + shutdown_mem_profiling(false); + schedule_work(&remove_allocinfo_work); +} + void __init alloc_tag_sec_init(void) { struct alloc_tag *last_codetag; @@ -855,7 +876,7 @@ static void *reserve_module_tags(struct module *mod, unsigned long size, align = 1; if (!ensure_alignment(align, &prepend)) { - shutdown_mem_profiling(true); + shutdown_mem_profiling_async(); pr_err("%s: alignment %lu is incompatible with allocation tag indexing. Memory allocation profiling is disabled!\n", mod->name, align); return ERR_PTR(-EINVAL); @@ -905,14 +926,14 @@ unlock: module_tags.size = offset + size; if (mem_alloc_profiling_enabled() && !tags_addressable()) { - shutdown_mem_profiling(true); + shutdown_mem_profiling_async(); pr_warn("With module %s there are too many tags to fit in %d page flag bits. Memory allocation profiling is disabled!\n", mod->name, NR_UNUSED_PAGEFLAG_BITS); } grow_res = vm_module_tags_populate(); if (grow_res) { - shutdown_mem_profiling(true); + shutdown_mem_profiling_async(); pr_err("Failed to allocate memory for allocation tags in the module %s. Memory allocation profiling is disabled!\n", mod->name); return ERR_PTR(grow_res); -- 2.53.0