From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 117334EB40 for ; Thu, 8 Feb 2024 21:27:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707427654; cv=none; b=nak7kV5eLXsrVSasvQEEClsHFN069f4VfcVBphQkLQT/3AgFZT2SQmNvWZ6zEYBubz3QWOEq9ckUpgi3ucBQY3ixJGrme4U5spdjrsrD4RVusrSkd/PUs/h0A2wsURuNh5cgDinsLL3UDPdNjCEBNc2mFUTzPhRUeOR/R49KwVI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707427654; c=relaxed/simple; bh=YB5e4ecNpkqs+ejowHknV6lS7BPTPsPirh6GSeBsjAk=; h=Date:To:From:Subject:Message-Id; b=Y/68rQxYnzTTdM0KgHSHBpLuPxSzBYgwKaKc+geK58SzWB3HzvbCg5pGOXzs8AU4DQGneQfLglnyUvCsXTGIw5zicbwkgQhhMduLB4GN55u3D1NC/m5Bm54mEPXhBrFEmFRIFFBdL1xgjiZ3HXYGKCGqCDgu3vONqiXti8k0/70= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=iA+g4RQu; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="iA+g4RQu" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7ECD2C433F1; Thu, 8 Feb 2024 21:27:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1707427653; bh=YB5e4ecNpkqs+ejowHknV6lS7BPTPsPirh6GSeBsjAk=; h=Date:To:From:Subject:From; b=iA+g4RQuL829+6kuDagFzmoIGngFstklIlwwzCfMj2vs04m4V+esx13tU4sRcc4L2 k70IXWdDA82TJqgl5d1ITvfms58RTHGW7vQQ5JwsQCHLSXNziklgptBJKO6ehIoM3f 9B+r2gZ7/kLVJEraKmQVrX5Io4lB1FhEG0pr4044= Date: Thu, 08 Feb 2024 13:27:32 -0800 To: mm-commits@vger.kernel.org,willy@infradead.org,vishal.l.verma@intel.com,torvalds@linux-foundation.org,snitzer@kernel.org,mpatocka@redhat.com,linux@armlinux.org.uk,david@fromorbit.com,dave.jiang@intel.com,dan.j.williams@intel.com,arnd@arndb.de,agk@redhat.com,mathieu.desnoyers@efficios.com,akpm@linux-foundation.org From: Andrew Morton Subject: + dax-check-for-data-cache-aliasing-at-runtime.patch added to mm-unstable branch Message-Id: <20240208212733.7ECD2C433F1@smtp.kernel.org> Precedence: bulk X-Mailing-List: mm-commits@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The patch titled Subject: dax: check for data cache aliasing at runtime has been added to the -mm mm-unstable branch. Its filename is dax-check-for-data-cache-aliasing-at-runtime.patch This patch will shortly appear at https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/dax-check-for-data-cache-aliasing-at-runtime.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: Mathieu Desnoyers Subject: dax: check for data cache aliasing at runtime Date: Thu, 8 Feb 2024 13:49:07 -0500 Replace the following fs/Kconfig:FS_DAX dependency: depends on !(ARM || MIPS || SPARC) By a runtime check within alloc_dax(). This runtime check returns ERR_PTR(-EOPNOTSUPP) if the @ops parameter is non-NULL (which means the kernel is using an aliased mapping) on an architecture which has data cache aliasing. Change the return value from NULL to PTR_ERR(-EOPNOTSUPP) for CONFIG_DAX=n for consistency. This is done in preparation for using cpu_dcache_is_aliasing() in a following change which will properly support architectures which detect data cache aliasing at runtime. Link: https://lkml.kernel.org/r/20240208184913.484340-7-mathieu.desnoyers@efficios.com Fixes: d92576f1167c ("dax: does not work correctly with virtual aliasing caches") Signed-off-by: Mathieu Desnoyers Cc: Linus Torvalds Cc: Dan Williams Cc: Vishal Verma Cc: Dave Jiang Cc: Matthew Wilcox Cc: Arnd Bergmann Cc: Russell King Cc: Alasdair Kergon Cc: Dave Chinner Cc: Mike Snitzer Cc: Mikulas Patocka Signed-off-by: Andrew Morton --- drivers/dax/super.c | 15 +++++++++++++++ fs/Kconfig | 1 - include/linux/dax.h | 6 +----- 3 files changed, 16 insertions(+), 6 deletions(-) --- a/drivers/dax/super.c~dax-check-for-data-cache-aliasing-at-runtime +++ a/drivers/dax/super.c @@ -319,6 +319,11 @@ EXPORT_SYMBOL_GPL(dax_alive); * that any fault handlers or operations that might have seen * dax_alive(), have completed. Any operations that start after * synchronize_srcu() has run will abort upon seeing !dax_alive(). + * + * Note, because alloc_dax() returns an ERR_PTR() on error, callers + * typically store its result into a local variable in order to check + * the result. Therefore, care must be taken to populate the struct + * device dax_dev field make sure the dax_dev is not leaked. */ void kill_dax(struct dax_device *dax_dev) { @@ -446,6 +451,16 @@ struct dax_device *alloc_dax(void *priva dev_t devt; int minor; + /* + * Unavailable on architectures with virtually aliased data caches, + * except for device-dax (NULL operations pointer), which does + * not use aliased mappings from the kernel. + */ + if (ops && (IS_ENABLED(CONFIG_ARM) || + IS_ENABLED(CONFIG_MIPS) || + IS_ENABLED(CONFIG_SPARC))) + return ERR_PTR(-EOPNOTSUPP); + if (WARN_ON_ONCE(ops && !ops->zero_page_range)) return ERR_PTR(-EINVAL); --- a/fs/Kconfig~dax-check-for-data-cache-aliasing-at-runtime +++ a/fs/Kconfig @@ -60,7 +60,6 @@ endif # BLOCK config FS_DAX bool "File system based Direct Access (DAX) support" depends on MMU - depends on !(ARM || MIPS || SPARC) depends on ZONE_DEVICE || FS_DAX_LIMITED select FS_IOMAP select DAX --- a/include/linux/dax.h~dax-check-for-data-cache-aliasing-at-runtime +++ a/include/linux/dax.h @@ -86,11 +86,7 @@ static inline void *dax_holder(struct da static inline struct dax_device *alloc_dax(void *private, const struct dax_operations *ops) { - /* - * Callers should check IS_ENABLED(CONFIG_DAX) to know if this - * NULL is an error or expected. - */ - return NULL; + return ERR_PTR(-EOPNOTSUPP); } static inline void put_dax(struct dax_device *dax_dev) { _ Patches currently in -mm which might be from mathieu.desnoyers@efficios.com are nvdimm-pmem-fix-leak-on-dax_add_host-failure.patch nvdimm-pmem-treat-alloc_dax-eopnotsupp-failure-as-non-fatal.patch dm-treat-alloc_dax-eopnotsupp-failure-as-non-fatal.patch dcssblk-handle-alloc_dax-eopnotsupp-failure.patch virtio-treat-alloc_dax-eopnotsupp-failure-as-non-fatal.patch dax-check-for-data-cache-aliasing-at-runtime.patch introduce-cpu_dcache_is_aliasing-across-all-architectures.patch dax-fix-incorrect-list-of-data-cache-aliasing-architectures.patch nvdimm-pmem-cleanup-alloc_dax-error-handling.patch dm-cleanup-alloc_dax-error-handling.patch dcssblk-cleanup-alloc_dax-error-handling.patch virtio-cleanup-alloc_dax-error-handling.patch