This is a note to let you know that I've just added the patch titled
mm, devm_memremap_pages: hold device_hotplug lock over mem_hotplug_{begin, done}
to the 4.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-devm_memremap_pages-hold-device_hotplug-lock-over-mem_hotplug_-begin-done.patch
and it can be found in the queue-4.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From b5d24fda9c3dce51fcb4eee459550a458eaaf1e2 Mon Sep 17 00:00:00 2001
From: Dan Williams <dan.j.williams@xxxxxxxxx>
Date: Fri, 24 Feb 2017 14:55:45 -0800
Subject: mm, devm_memremap_pages: hold device_hotplug lock over mem_hotplug_{begin, done}
From: Dan Williams <dan.j.williams@xxxxxxxxx>
commit b5d24fda9c3dce51fcb4eee459550a458eaaf1e2 upstream.
The mem_hotplug_{begin,done} lock coordinates with {get,put}_online_mems()
to hold off "readers" of the current state of memory from new hotplug
actions. mem_hotplug_begin() expects exclusive access, via the
device_hotplug lock, to set mem_hotplug.active_writer. Calling
mem_hotplug_begin() without locking device_hotplug can lead to
corrupting mem_hotplug.refcount and missed wakeups / soft lockups.
[dan.j.williams@xxxxxxxxx: v2]
Link: http://lkml.kernel.org/r/148728203365.38457.17804568297887708345.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Link: http://lkml.kernel.org/r/148693885680.16345.17802627926777862337.stgit@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
Fixes: f931ab479dd2 ("mm: fix devm_memremap_pages crash, use mem_hotplug_{begin, done}")
Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
Reported-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Toshi Kani <toshi.kani@xxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Logan Gunthorpe <logang@xxxxxxxxxxxx>
Cc: Masayoshi Mizuma <m.mizuma@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
kernel/memremap.c | 6 ++++++
1 file changed, 6 insertions(+)
--- a/kernel/memremap.c
+++ b/kernel/memremap.c
@@ -246,9 +246,13 @@ static void devm_memremap_pages_release(
/* pages are dead and unused, undo the arch mapping */
align_start = res->start & ~(SECTION_SIZE - 1);
align_size = ALIGN(resource_size(res), SECTION_SIZE);
+
+ lock_device_hotplug();
mem_hotplug_begin();
arch_remove_memory(align_start, align_size);
mem_hotplug_done();
+ unlock_device_hotplug();
+
untrack_pfn(NULL, PHYS_PFN(align_start), align_size);
pgmap_radix_release(res);
dev_WARN_ONCE(dev, pgmap->altmap && pgmap->altmap->alloc,
@@ -360,9 +364,11 @@ void *devm_memremap_pages(struct device
if (error)
goto err_pfn_remap;
+ lock_device_hotplug();
mem_hotplug_begin();
error = arch_add_memory(nid, align_start, align_size, true);
mem_hotplug_done();
+ unlock_device_hotplug();
if (error)
goto err_add_memory;
Patches currently in stable-queue which might be from dan.j.williams@xxxxxxxxx are
queue-4.10/mm-devm_memremap_pages-hold-device_hotplug-lock-over-mem_hotplug_-begin-done.patch