From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pg0-f71.google.com (mail-pg0-f71.google.com [74.125.83.71]) by kanga.kvack.org (Postfix) with ESMTP id 5956F681021 for ; Thu, 16 Feb 2017 22:08:04 -0500 (EST) Received: by mail-pg0-f71.google.com with SMTP id 65so47584022pgi.7 for ; Thu, 16 Feb 2017 19:08:04 -0800 (PST) Received: from mga05.intel.com (mga05.intel.com. [192.55.52.43]) by mx.google.com with ESMTPS id l1si8858931plk.130.2017.02.16.19.08.03 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 16 Feb 2017 19:08:03 -0800 (PST) Date: Thu, 16 Feb 2017 20:08:02 -0700 From: Ross Zwisler Subject: Re: [PATCH v2 2/2] mm: validate device_hotplug is held for memory hotplug Message-ID: <20170217030802.GA27382@linux.intel.com> References: <148728202805.38457.18028105614854319884.stgit@dwillia2-desk3.amr.corp.intel.com> <148728203880.38457.1158394701925100383.stgit@dwillia2-desk3.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <148728203880.38457.1158394701925100383.stgit@dwillia2-desk3.amr.corp.intel.com> Sender: owner-linux-mm@kvack.org List-ID: To: Dan Williams Cc: akpm@linux-foundation.org, Michal Hocko , linux-nvdimm@lists.01.org, Greg Kroah-Hartman , linux-mm@kvack.org, Ben Hutchings , Vlastimil Babka On Thu, Feb 16, 2017 at 01:53:58PM -0800, Dan Williams wrote: > mem_hotplug_begin() assumes that it can set mem_hotplug.active_writer > and run the hotplug process without racing another thread. Validate this > assumption with a lockdep assertion. > > Cc: Michal Hocko > Cc: Toshi Kani > Cc: Vlastimil Babka > Cc: Logan Gunthorpe > Cc: Greg Kroah-Hartman > Reported-by: Ben Hutchings > Signed-off-by: Dan Williams > --- > drivers/base/core.c | 5 +++++ > include/linux/device.h | 1 + > mm/memory_hotplug.c | 2 ++ > 3 files changed, 8 insertions(+) > > diff --git a/drivers/base/core.c b/drivers/base/core.c > index 8c25e68e67d7..3050e6f99403 100644 > --- a/drivers/base/core.c > +++ b/drivers/base/core.c > @@ -638,6 +638,11 @@ int lock_device_hotplug_sysfs(void) > return restart_syscall(); > } > > +void assert_held_device_hotplug(void) > +{ > + lockdep_assert_held(&device_hotplug_lock); > +} > + > #ifdef CONFIG_BLOCK > static inline int device_is_not_partition(struct device *dev) > { > diff --git a/include/linux/device.h b/include/linux/device.h > index 491b4c0ca633..815965ee55dd 100644 > --- a/include/linux/device.h > +++ b/include/linux/device.h > @@ -1135,6 +1135,7 @@ static inline bool device_supports_offline(struct device *dev) > extern void lock_device_hotplug(void); > extern void unlock_device_hotplug(void); > extern int lock_device_hotplug_sysfs(void); > +void assert_held_device_hotplug(void); > extern int device_offline(struct device *dev); > extern int device_online(struct device *dev); > extern void set_primary_fwnode(struct device *dev, struct fwnode_handle *fwnode); > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index b8c11e063ff0..1635a2a085e5 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -126,6 +126,8 @@ void put_online_mems(void) > > void mem_hotplug_begin(void) > { > + assert_held_device_hotplug(); What's the benefit to defining assert_held_device_hotplug() as a one line wrapper, instead of just calling lockdep_assert_held(&device_hotplug_lock) directly? > + > mem_hotplug.active_writer = current; > > memhp_lock_acquire(); > > _______________________________________________ > Linux-nvdimm mailing list > Linux-nvdimm@lists.01.org > https://lists.01.org/mailman/listinfo/linux-nvdimm -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org