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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 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