FAILED: patch "[PATCH] mm/memory_hotplug: fix unpaired mem_hotplug_begin/done" failed to apply to 4.19-stable tree

FAILED: patch "[PATCH] mm/memory_hotplug: fix unpaired mem_hotplug_begin/done" failed to apply to 4.19-stable tree

[gregkh]

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;
 }
 
 /**

RE: FAILED: patch "[PATCH] mm/memory_hotplug: fix unpaired mem_hotplug_begin/done" failed to apply to 4.19-stable tree

[Justin He]

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/memory_hotplug.c?h=linux-4.19.y#n1913.
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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Re: FAILED: patch "[PATCH] mm/memory_hotplug: fix unpaired mem_hotplug_begin/done" failed to apply to 4.19-stable tree

[gregkh]

On Thu, Aug 20, 2020 at 02:27:40AM +0000, Justin He wrote:
> 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/memory_hotplug.c?h=linux-4.19.y#n1913.
> Looks like stable tree v4.19 hasn't applied eca499ab3 but applied f1037ec0c.
> Hence I don't think v4.19 needs this patch.

Thanks, I'll just leave this out of 4.19.y for now then.

greg k-h