Hi Greg, If anybody wants to backport it to stable tree, there are 2 pre-condition for this commit ("[PATCH] mm/memory_hotplug: fix unpaired mem_hotplug_begin/done")
1. eca499ab3 ("mm/hotplug: make remove_memory() interface usable") applied in v5.2, it disabled the BUG() when check_memblock_offlined_cb() failed. 2. f1037ec0c ("mm/memory_hotplug: fix remove_memory() lockdep splat") in v5.5, it introduced the unpair but depends on eca499ab3
I checked https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/tree/mm/mem.... Looks like stable tree v4.19 hasn't applied eca499ab3 but applied f1037ec0c. Hence I don't think v4.19 needs this patch.
-- Cheers, Justin (Jia He)
-----Original Message----- From: gregkh@linuxfoundation.org gregkh@linuxfoundation.org Sent: Wednesday, August 19, 2020 8:29 PM To: Justin He Justin.He@arm.com; Jonathan.Cameron@Huawei.com; Kaly Xin Kaly.Xin@arm.com; akpm@linux-foundation.org; bhe@redhat.com; bp@alien8.de; Catalin Marinas Catalin.Marinas@arm.com; dalias@libc.org; dan.j.williams@intel.com; dave.hansen@linux.intel.com; dave.jiang@intel.com; david@redhat.com; fenghua.yu@intel.com; hpa@zytor.com; hslester96@gmail.com; logang@deltatee.com; luto@kernel.org; masahiroy@kernel.org; mhocko@suse.com; mingo@redhat.com; peterz@infradead.org; rppt@linux.ibm.com; stable@vger.kernel.org; tglx@linutronix.de; tony.luck@intel.com; torvalds@linux-foundation.org; vishal.l.verma@intel.com; will@kernel.org; ysato@users.sourceforge.jp Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] mm/memory_hotplug: fix unpaired mem_hotplug_begin/done" failed to apply to 4.19-stable tree
The patch below does not apply to the 4.19-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
From b4223a510e2ab1bf0f971d50af7c1431014b25ad Mon Sep 17 00:00:00 2001 From: Jia He justin.he@arm.com Date: Tue, 11 Aug 2020 18:32:20 -0700 Subject: [PATCH] mm/memory_hotplug: fix unpaired mem_hotplug_begin/done
When check_memblock_offlined_cb() returns failed rc(e.g. the memblock is online at that time), mem_hotplug_begin/done is unpaired in such case.
Therefore a warning: Call Trace: percpu_up_write+0x33/0x40 try_remove_memory+0x66/0x120 ? _cond_resched+0x19/0x30 remove_memory+0x2b/0x40 dev_dax_kmem_remove+0x36/0x72 [kmem] device_release_driver_internal+0xf0/0x1c0 device_release_driver+0x12/0x20 bus_remove_device+0xe1/0x150 device_del+0x17b/0x3e0 unregister_dev_dax+0x29/0x60 devm_action_release+0x15/0x20 release_nodes+0x19a/0x1e0 devres_release_all+0x3f/0x50 device_release_driver_internal+0x100/0x1c0 driver_detach+0x4c/0x8f bus_remove_driver+0x5c/0xd0 driver_unregister+0x31/0x50 dax_pmem_exit+0x10/0xfe0 [dax_pmem]
Fixes: f1037ec0cc8a ("mm/memory_hotplug: fix remove_memory() lockdep splat") Signed-off-by: Jia He justin.he@arm.com Signed-off-by: Andrew Morton akpm@linux-foundation.org Reviewed-by: David Hildenbrand david@redhat.com Acked-by: Michal Hocko mhocko@suse.com Acked-by: Dan Williams dan.j.williams@intel.com Cc: stable@vger.kernel.org[5.6+] Cc: Andy Lutomirski luto@kernel.org Cc: Baoquan He bhe@redhat.com Cc: Borislav Petkov bp@alien8.de Cc: Catalin Marinas catalin.marinas@arm.com Cc: Chuhong Yuan hslester96@gmail.com Cc: Dave Hansen dave.hansen@linux.intel.com Cc: Dave Jiang dave.jiang@intel.com Cc: Fenghua Yu fenghua.yu@intel.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: Ingo Molnar mingo@redhat.com Cc: Jonathan Cameron Jonathan.Cameron@Huawei.com Cc: Kaly Xin Kaly.Xin@arm.com Cc: Logan Gunthorpe logang@deltatee.com Cc: Masahiro Yamada masahiroy@kernel.org Cc: Mike Rapoport rppt@linux.ibm.com Cc: Peter Zijlstra peterz@infradead.org Cc: Rich Felker dalias@libc.org Cc: Thomas Gleixner tglx@linutronix.de Cc: Tony Luck tony.luck@intel.com Cc: Vishal Verma vishal.l.verma@intel.com Cc: Will Deacon will@kernel.org Cc: Yoshinori Sato ysato@users.sourceforge.jp Link: http://lkml.kernel.org/r/20200710031619.18762-3-justin.he@arm.com Signed-off-by: Linus Torvalds torvalds@linux-foundation.org
diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index 6289a909ea36..ce3d858319bd 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1757,7 +1757,7 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size) */ rc = walk_memory_blocks(start, size, NULL, check_memblock_offlined_cb); if (rc) -goto done; +return rc;
/* remove memmap entry */ firmware_map_remove(start, start + size, "System RAM"); @@ -1781,9 +1781,8 @@ static int __ref try_remove_memory(int nid, u64 start, u64 size)
try_offline_node(nid);
-done: mem_hotplug_done(); -return rc; +return 0; }
/**
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