This is a note to let you know that I've just added the patch titled
mm/memory_hotplug: make remove_memory() take the device_hotplug_lock
to the 4.19-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-memory_hotplug-make-remove_memory-take-the-device_hotplug_lock.patch
and it can be found in the queue-4.19 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From foo@baz Tue 28 Jan 2020 02:32:10 PM CET
From: David Hildenbrand <david@xxxxxxxxxx>
Date: Tue, 28 Jan 2020 10:49:58 +0100
Subject: mm/memory_hotplug: make remove_memory() take the device_hotplug_lock
To: stable@xxxxxxxxxxxxxxx
Cc: linux-mm@xxxxxxxxx, Michal Hocko <mhocko@xxxxxxxx>, Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>, Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>, "Aneesh Kumar K . V" <aneesh.kumar@xxxxxxxxxxxxx>, Baoquan He <bhe@xxxxxxxxxx>, Dan Williams <dan.j.williams@xxxxxxxxx>, Oscar Salvador <osalvador@xxxxxxx>, Wei Yang <richard.weiyang@xxxxxxxxx>, David Hildenbrand <david@xxxxxxxxxx>
Message-ID: <20200128095021.8076-2-david@xxxxxxxxxx>
From: David Hildenbrand <david@xxxxxxxxxx>
commit d15e59260f62bd5e0f625cf5f5240f6ffac78ab6 upstream.
Patch series "mm: online/offline_pages called w.o. mem_hotplug_lock", v3.
Reading through the code and studying how mem_hotplug_lock is to be used,
I noticed that there are two places where we can end up calling
device_online()/device_offline() - online_pages()/offline_pages() without
the mem_hotplug_lock. And there are other places where we call
device_online()/device_offline() without the device_hotplug_lock.
While e.g.
echo "online" > /sys/devices/system/memory/memory9/state
is fine, e.g.
echo 1 > /sys/devices/system/memory/memory9/online
Will not take the mem_hotplug_lock. However the device_lock() and
device_hotplug_lock.
E.g. via memory_probe_store(), we can end up calling
add_memory()->online_pages() without the device_hotplug_lock. So we can
have concurrent callers in online_pages(). We e.g. touch in
online_pages() basically unprotected zone->present_pages then.
Looks like there is a longer history to that (see Patch #2 for details),
and fixing it to work the way it was intended is not really possible. We
would e.g. have to take the mem_hotplug_lock in device/base/core.c, which
sounds wrong.
Summary: We had a lock inversion on mem_hotplug_lock and device_lock().
More details can be found in patch 3 and patch 6.
I propose the general rules (documentation added in patch 6):
1. add_memory/add_memory_resource() must only be called with
device_hotplug_lock.
2. remove_memory() must only be called with device_hotplug_lock. This is
already documented and holds for all callers.
3. device_online()/device_offline() must only be called with
device_hotplug_lock. This is already documented and true for now in core
code. Other callers (related to memory hotplug) have to be fixed up.
4. mem_hotplug_lock is taken inside of add_memory/remove_memory/
online_pages/offline_pages.
To me, this looks way cleaner than what we have right now (and easier to
verify). And looking at the documentation of remove_memory, using
lock_device_hotplug also for add_memory() feels natural.
This patch (of 6):
remove_memory() is exported right now but requires the
device_hotplug_lock, which is not exported. So let's provide a variant
that takes the lock and only export that one.
The lock is already held in
arch/powerpc/platforms/pseries/hotplug-memory.c
drivers/acpi/acpi_memhotplug.c
arch/powerpc/platforms/powernv/memtrace.c
Apart from that, there are not other users in the tree.
Link: http://lkml.kernel.org/r/20180925091457.28651-2-david@xxxxxxxxxx
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Reviewed-by: Pavel Tatashin <pavel.tatashin@xxxxxxxxxxxxx>
Reviewed-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Reviewed-by: Rashmica Gupta <rashmica.g@xxxxxxxxx>
Reviewed-by: Oscar Salvador <osalvador@xxxxxxx>
Cc: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx>
Cc: Paul Mackerras <paulus@xxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxxxxxxxx>
Cc: Len Brown <lenb@xxxxxxxxxx>
Cc: Rashmica Gupta <rashmica.g@xxxxxxxxx>
Cc: Michael Neuling <mikey@xxxxxxxxxxx>
Cc: Balbir Singh <bsingharora@xxxxxxxxx>
Cc: Nathan Fontenot <nfont@xxxxxxxxxxxxxxxxxx>
Cc: John Allen <jallen@xxxxxxxxxxxxxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Cc: YASUAKI ISHIMATSU <yasu.isimatu@xxxxxxxxx>
Cc: Mathieu Malaterre <malat@xxxxxxxxxx>
Cc: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Cc: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>
Cc: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Cc: Jonathan Corbet <corbet@xxxxxxx>
Cc: Juergen Gross <jgross@xxxxxxxx>
Cc: Kate Stewart <kstewart@xxxxxxxxxxxxxxxxxxx>
Cc: "K. Y. Srinivasan" <kys@xxxxxxxxxxxxx>
Cc: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Cc: Philippe Ombredanne <pombredanne@xxxxxxxx>
Cc: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: David Hildenbrand <david@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/platforms/powernv/memtrace.c | 2 +-
arch/powerpc/platforms/pseries/hotplug-memory.c | 6 +++---
drivers/acpi/acpi_memhotplug.c | 2 +-
include/linux/memory_hotplug.h | 3 ++-
mm/memory_hotplug.c | 9 ++++++++-
5 files changed, 15 insertions(+), 7 deletions(-)
--- a/arch/powerpc/platforms/powernv/memtrace.c
+++ b/arch/powerpc/platforms/powernv/memtrace.c
@@ -122,7 +122,7 @@ static u64 memtrace_alloc_node(u32 nid,
*/
end_pfn = base_pfn + nr_pages;
for (pfn = base_pfn; pfn < end_pfn; pfn += bytes>> PAGE_SHIFT) {
- remove_memory(nid, pfn << PAGE_SHIFT, bytes);
+ __remove_memory(nid, pfn << PAGE_SHIFT, bytes);
}
unlock_device_hotplug();
return base_pfn << PAGE_SHIFT;
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -301,7 +301,7 @@ static int pseries_remove_memblock(unsig
nid = memory_add_physaddr_to_nid(base);
for (i = 0; i < sections_per_block; i++) {
- remove_memory(nid, base, MIN_MEMORY_BLOCK_SIZE);
+ __remove_memory(nid, base, MIN_MEMORY_BLOCK_SIZE);
base += MIN_MEMORY_BLOCK_SIZE;
}
@@ -393,7 +393,7 @@ static int dlpar_remove_lmb(struct drmem
block_sz = pseries_memory_block_size();
nid = memory_add_physaddr_to_nid(lmb->base_addr);
- remove_memory(nid, lmb->base_addr, block_sz);
+ __remove_memory(nid, lmb->base_addr, block_sz);
/* Update memory regions for memory remove */
memblock_remove(lmb->base_addr, block_sz);
@@ -680,7 +680,7 @@ static int dlpar_add_lmb(struct drmem_lm
rc = dlpar_online_lmb(lmb);
if (rc) {
- remove_memory(nid, lmb->base_addr, block_sz);
+ __remove_memory(nid, lmb->base_addr, block_sz);
invalidate_lmb_associativity_index(lmb);
} else {
lmb->flags |= DRCONF_MEM_ASSIGNED;
--- a/drivers/acpi/acpi_memhotplug.c
+++ b/drivers/acpi/acpi_memhotplug.c
@@ -282,7 +282,7 @@ static void acpi_memory_remove_memory(st
nid = memory_add_physaddr_to_nid(info->start_addr);
acpi_unbind_memory_blocks(info);
- remove_memory(nid, info->start_addr, info->length);
+ __remove_memory(nid, info->start_addr, info->length);
list_del(&info->list);
kfree(info);
}
--- a/include/linux/memory_hotplug.h
+++ b/include/linux/memory_hotplug.h
@@ -303,6 +303,7 @@ extern bool is_mem_section_removable(uns
extern void try_offline_node(int nid);
extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
extern void remove_memory(int nid, u64 start, u64 size);
+extern void __remove_memory(int nid, u64 start, u64 size);
#else
static inline bool is_mem_section_removable(unsigned long pfn,
@@ -319,6 +320,7 @@ static inline int offline_pages(unsigned
}
static inline void remove_memory(int nid, u64 start, u64 size) {}
+static inline void __remove_memory(int nid, u64 start, u64 size) {}
#endif /* CONFIG_MEMORY_HOTREMOVE */
extern void __ref free_area_init_core_hotplug(int nid);
@@ -333,7 +335,6 @@ extern void move_pfn_range_to_zone(struc
unsigned long nr_pages, struct vmem_altmap *altmap);
extern int offline_pages(unsigned long start_pfn, unsigned long nr_pages);
extern bool is_memblock_offlined(struct memory_block *mem);
-extern void remove_memory(int nid, u64 start, u64 size);
extern int sparse_add_one_section(struct pglist_data *pgdat,
unsigned long start_pfn, struct vmem_altmap *altmap);
extern void sparse_remove_one_section(struct zone *zone, struct mem_section *ms,
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1893,7 +1893,7 @@ EXPORT_SYMBOL(try_offline_node);
* and online/offline operations before this call, as required by
* try_offline_node().
*/
-void __ref remove_memory(int nid, u64 start, u64 size)
+void __ref __remove_memory(int nid, u64 start, u64 size)
{
int ret;
@@ -1922,5 +1922,12 @@ void __ref remove_memory(int nid, u64 st
mem_hotplug_done();
}
+
+void remove_memory(int nid, u64 start, u64 size)
+{
+ lock_device_hotplug();
+ __remove_memory(nid, start, size);
+ unlock_device_hotplug();
+}
EXPORT_SYMBOL_GPL(remove_memory);
#endif /* CONFIG_MEMORY_HOTREMOVE */
Patches currently in stable-queue which might be from david@xxxxxxxxxx are
queue-4.19/mm-memory_hotplug-remove-memory-block-devices-before-arch_remove_memory.patch
queue-4.19/mm-hotplug-kill-is_dev_zone-usage-in-__remove_pages.patch
queue-4.19/mm-memory_hotplug-create-memory-block-devices-after-arch_add_memory.patch
queue-4.19/drivers-base-memory-pass-a-block_id-to-init_memory_block.patch
queue-4.19/drivers-base-memory.c-clean-up-relics-in-function-parameters.patch
queue-4.19/mm-memory_hotplug-update-a-comment-in-unregister_memory.patch
queue-4.19/mm-memory_hotplug-shrink-zones-when-offlining-memory.patch
queue-4.19/mm-memory_hotplug-make-unregister_memory_block_under_nodes-never-fail.patch
queue-4.19/mm-memunmap-don-t-access-uninitialized-memmap-in-memunmap_pages.patch
queue-4.19/mm-memory_hotplug-make-__remove_section-never-fail.patch
queue-4.19/mm-sparse-drop-pgdat_resize_lock-in-sparse_add-remove_one_section.patch
queue-4.19/mm-memory_hotplug-make-unregister_memory_section-never-fail.patch
queue-4.19/mm-memory_hotplug-release-memory-resource-after-arch_remove_memory.patch
queue-4.19/mm-memory_hotplug-add-nid-parameter-to-arch_remove_memory.patch
queue-4.19/powerpc-mm-fix-section-mismatch-warning.patch
queue-4.19/mm-memory_hotplug-allow-arch_remove_memory-without-config_memory_hotremove.patch
queue-4.19/mm-memory_hotplug-make-remove_memory-take-the-device_hotplug_lock.patch
queue-4.19/mm-memory_hotplug-make-__remove_pages-and-arch_remove_memory-never-fail.patch
queue-4.19/mm-memory_hotplug-fix-try_offline_node.patch
queue-4.19/mm-memory_hotplug-remove-zone-parameter-from-sparse_remove_one_section.patch
queue-4.19/drivers-base-memory.c-remove-an-unnecessary-check-on-nr_mem_sections.patch
queue-4.19/drivers-base-node.c-simplify-unregister_memory_block_under_nodes.patch
queue-4.19/s390x-mm-implement-arch_remove_memory.patch
queue-4.19/mm-sparse-pass-nid-instead-of-pgdat-to-sparse_add_one_section.patch
