mm/memory_hotplug: fix online/offline_pages called w.o. mem_hotplug_lock
There seem to be some problems as result ofhifive-unleashed-5.130467e0b3b("mm, hotplug: fix concurrent memory hot-add deadlock"), which tried to fix a possible lock inversion reported and discussed in [1] due to the two locks a) device_lock() b) mem_hotplug_lock While add_memory() first takes b), followed by a) during bus_probe_device(), onlining of memory from user space first took a), followed by b), exposing a possible deadlock. In [1], and it was decided to not make use of device_hotplug_lock, but rather to enforce a locking order. The problems I spotted related to this: 1. Memory block device attributes: While .state first calls mem_hotplug_begin() and the calls device_online() - which takes device_lock() - .online does no longer call mem_hotplug_begin(), so effectively calls online_pages() without mem_hotplug_lock. 2. device_online() should be called under device_hotplug_lock, however onlining memory during add_memory() does not take care of that. In addition, I think there is also something wrong about the locking in 3. arch/powerpc/platforms/powernv/memtrace.c calls offline_pages() without locks. This was introduced after30467e0b3b. And skimming over the code, I assume it could need some more care in regards to locking (e.g. device_online() called without device_hotplug_lock. This will be addressed in the following patches. Now that we hold the device_hotplug_lock when - adding memory (e.g. via add_memory()/add_memory_resource()) - removing memory (e.g. via remove_memory()) - device_online()/device_offline() We can move mem_hotplug_lock usage back into online_pages()/offline_pages(). Why is mem_hotplug_lock still needed? Essentially to make get_online_mems()/put_online_mems() be very fast (relying on device_hotplug_lock would be very slow), and to serialize against addition of memory that does not create memory block devices (hmm). [1] http://driverdev.linuxdriverproject.org/pipermail/ driverdev-devel/ 2015-February/065324.html This patch is partly based on a patch by Vitaly Kuznetsov. Link: http://lkml.kernel.org/r/20180925091457.28651-4-david@redhat.com Signed-off-by: David Hildenbrand <david@redhat.com> Reviewed-by: Pavel Tatashin <pavel.tatashin@microsoft.com> Reviewed-by: Rashmica Gupta <rashmica.g@gmail.com> Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: Paul Mackerras <paulus@samba.org> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net> Cc: Len Brown <lenb@kernel.org> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: "K. Y. Srinivasan" <kys@microsoft.com> Cc: Haiyang Zhang <haiyangz@microsoft.com> Cc: Stephen Hemminger <sthemmin@microsoft.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: Juergen Gross <jgross@suse.com> Cc: Rashmica Gupta <rashmica.g@gmail.com> Cc: Michael Neuling <mikey@neuling.org> Cc: Balbir Singh <bsingharora@gmail.com> Cc: Kate Stewart <kstewart@linuxfoundation.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Philippe Ombredanne <pombredanne@nexb.com> Cc: Pavel Tatashin <pavel.tatashin@microsoft.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Oscar Salvador <osalvador@suse.de> Cc: YASUAKI ISHIMATSU <yasu.isimatu@gmail.com> Cc: Mathieu Malaterre <malat@debian.org> Cc: John Allen <jallen@linux.vnet.ibm.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com> Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
David Hildenbrand
Linus Torvalds
parent
8df1d0e4a2
commit
381eab4a6e
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@ -228,7 +228,6 @@ static bool pages_correctly_probed(unsigned long start_pfn)
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/*
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* MEMORY_HOTPLUG depends on SPARSEMEM in mm/Kconfig, so it is
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* OK to have direct references to sparsemem variables in here.
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* Must already be protected by mem_hotplug_begin().
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*/
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static int
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memory_block_action(unsigned long phys_index, unsigned long action, int online_type)
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@ -294,7 +293,6 @@ static int memory_subsys_online(struct device *dev)
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if (mem->online_type < 0)
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mem->online_type = MMOP_ONLINE_KEEP;
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/* Already under protection of mem_hotplug_begin() */
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ret = memory_block_change_state(mem, MEM_ONLINE, MEM_OFFLINE);
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/* clear online_type */
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@ -341,19 +339,11 @@ store_mem_state(struct device *dev,
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goto err;
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}
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/*
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* Memory hotplug needs to hold mem_hotplug_begin() for probe to find
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* the correct memory block to online before doing device_online(dev),
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* which will take dev->mutex. Take the lock early to prevent an
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* inversion, memory_subsys_online() callbacks will be implemented by
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* assuming it's already protected.
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*/
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mem_hotplug_begin();
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switch (online_type) {
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case MMOP_ONLINE_KERNEL:
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case MMOP_ONLINE_MOVABLE:
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case MMOP_ONLINE_KEEP:
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/* mem->online_type is protected by device_hotplug_lock */
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mem->online_type = online_type;
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ret = device_online(&mem->dev);
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break;
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@ -364,7 +354,6 @@ store_mem_state(struct device *dev,
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ret = -EINVAL; /* should never happen */
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}
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mem_hotplug_done();
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err:
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unlock_device_hotplug();
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@ -838,7 +838,6 @@ static struct zone * __meminit move_pfn_range(int online_type, int nid,
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return zone;
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}
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/* Must be protected by mem_hotplug_begin() or a device_lock */
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int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_type)
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{
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unsigned long flags;
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@ -850,6 +849,8 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
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struct memory_notify arg;
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struct memory_block *mem;
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mem_hotplug_begin();
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/*
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* We can't use pfn_to_nid() because nid might be stored in struct page
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* which is not yet initialized. Instead, we find nid from memory block.
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@ -914,6 +915,7 @@ int __ref online_pages(unsigned long pfn, unsigned long nr_pages, int online_typ
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if (onlined_pages)
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memory_notify(MEM_ONLINE, &arg);
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mem_hotplug_done();
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return 0;
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failed_addition:
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@ -921,6 +923,7 @@ failed_addition:
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(unsigned long long) pfn << PAGE_SHIFT,
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(((unsigned long long) pfn + nr_pages) << PAGE_SHIFT) - 1);
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memory_notify(MEM_CANCEL_ONLINE, &arg);
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mem_hotplug_done();
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return ret;
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}
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#endif /* CONFIG_MEMORY_HOTPLUG_SPARSE */
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@ -1125,20 +1128,20 @@ int __ref add_memory_resource(int nid, struct resource *res, bool online)
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/* create new memmap entry */
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firmware_map_add_hotplug(start, start + size, "System RAM");
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/* device_online() will take the lock when calling online_pages() */
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mem_hotplug_done();
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/* online pages if requested */
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if (online)
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walk_memory_range(PFN_DOWN(start), PFN_UP(start + size - 1),
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NULL, online_memory_block);
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goto out;
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return ret;
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error:
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/* rollback pgdat allocation and others */
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if (new_node)
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rollback_node_hotadd(nid);
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memblock_remove(start, size);
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out:
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mem_hotplug_done();
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return ret;
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}
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@ -1555,10 +1558,16 @@ static int __ref __offline_pages(unsigned long start_pfn,
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return -EINVAL;
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if (!IS_ALIGNED(end_pfn, pageblock_nr_pages))
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return -EINVAL;
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mem_hotplug_begin();
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/* This makes hotplug much easier...and readable.
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we assume this for now. .*/
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if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start, &valid_end))
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if (!test_pages_in_a_zone(start_pfn, end_pfn, &valid_start,
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&valid_end)) {
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mem_hotplug_done();
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return -EINVAL;
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}
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zone = page_zone(pfn_to_page(valid_start));
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node = zone_to_nid(zone);
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@ -1567,8 +1576,10 @@ static int __ref __offline_pages(unsigned long start_pfn,
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/* set above range as isolated */
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ret = start_isolate_page_range(start_pfn, end_pfn,
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MIGRATE_MOVABLE, true);
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if (ret)
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if (ret) {
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mem_hotplug_done();
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return ret;
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}
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arg.start_pfn = start_pfn;
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arg.nr_pages = nr_pages;
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@ -1639,6 +1650,7 @@ repeat:
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writeback_set_ratelimit();
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memory_notify(MEM_OFFLINE, &arg);
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mem_hotplug_done();
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return 0;
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failed_removal:
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@ -1648,10 +1660,10 @@ failed_removal:
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memory_notify(MEM_CANCEL_OFFLINE, &arg);
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/* pushback to free area */
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undo_isolate_page_range(start_pfn, end_pfn, MIGRATE_MOVABLE);
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mem_hotplug_done();
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return ret;
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}
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/* Must be protected by mem_hotplug_begin() or a device_lock */
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int offline_pages(unsigned long start_pfn, unsigned long nr_pages)
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{
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return __offline_pages(start_pfn, start_pfn + nr_pages);
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