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V" , Baoquan He , Dan Williams , Oscar Salvador , Wei Yang , David Hildenbrand Subject: [PATCH for 4.19-stable v2 22/24] mm/memunmap: don't access uninitialized memmap in memunmap_pages() Date: Tue, 21 Jan 2020 19:01:48 +0100 Message-Id: <20200121180150.37454-23-david@redhat.com> In-Reply-To: <20200121180150.37454-1-david@redhat.com> References: <20200121180150.37454-1-david@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: "Aneesh Kumar K.V" commit 77e080e7680e1e615587352f70c87b9e98126d03 upstream. -- snip -- - Missing mm/hmm.c and kernel/memremap.c unification. -- hmm code does not need fixes (no altmap) - Missing 7cc7867fb061 ("mm/devm_memremap_pages: enable sub-section remap= ") -- snip -- Patch series "mm/memory_hotplug: Shrink zones before removing memory", v6. This series fixes the access of uninitialized memmaps when shrinking zones/nodes and when removing memory. Also, it contains all fixes for crashes that can be triggered when removing certain namespace using memunmap_pages() - ZONE_DEVICE, reported by Aneesh. We stop trying to shrink ZONE_DEVICE, as it's buggy, fixing it would be more involved (we don't have SECTION_IS_ONLINE as an indicator), and shrinking is only of limited use (set_zone_contiguous() cannot detect the ZONE_DEVICE as contiguous). We continue shrinking !ZONE_DEVICE zones, however, I reduced the amount of code to a minimum. Shrinking is especially necessary to keep zone->contiguous set where possible, especially, on memory unplug of DIMMs at zone boundaries. -------------------------------------------------------------------------= - Zones are now properly shrunk when offlining memory blocks or when onlining failed. This allows to properly shrink zones on memory unplug even if the separate memory blocks of a DIMM were onlined to different zones or re-onlined to a different zone after offlining. Example: :/# cat /proc/zoneinfo Node 1, zone Movable spanned 0 present 0 managed 0 :/# echo "online_movable" > /sys/devices/system/memory/memory41/state :/# echo "online_movable" > /sys/devices/system/memory/memory43/state :/# cat /proc/zoneinfo Node 1, zone Movable spanned 98304 present 65536 managed 65536 :/# echo 0 > /sys/devices/system/memory/memory43/online :/# cat /proc/zoneinfo Node 1, zone Movable spanned 32768 present 32768 managed 32768 :/# echo 0 > /sys/devices/system/memory/memory41/online :/# cat /proc/zoneinfo Node 1, zone Movable spanned 0 present 0 managed 0 This patch (of 10): With an altmap, the memmap falling into the reserved altmap space are not initialized and, therefore, contain a garbage NID and a garbage zone. Make sure to read the NID/zone from a memmap that was initialized. This fixes a kernel crash that is observed when destroying a namespace: kernel BUG at include/linux/mm.h:1107! cpu 0x1: Vector: 700 (Program Check) at [c000000274087890] pc: c0000000004b9728: memunmap_pages+0x238/0x340 lr: c0000000004b9724: memunmap_pages+0x234/0x340 ... pid =3D 3669, comm =3D ndctl kernel BUG at include/linux/mm.h:1107! devm_action_release+0x30/0x50 release_nodes+0x268/0x2d0 device_release_driver_internal+0x174/0x240 unbind_store+0x13c/0x190 drv_attr_store+0x44/0x60 sysfs_kf_write+0x70/0xa0 kernfs_fop_write+0x1ac/0x290 __vfs_write+0x3c/0x70 vfs_write+0xe4/0x200 ksys_write+0x7c/0x140 system_call+0x5c/0x68 The "page_zone(pfn_to_page(pfn)" was introduced by 69324b8f4833 ("mm, devm_memremap_pages: add MEMORY_DEVICE_PRIVATE support"), however, I think we will never have driver reserved memory with MEMORY_DEVICE_PRIVATE (no altmap AFAIKS). [david@redhat.com: minimze code changes, rephrase description] Link: http://lkml.kernel.org/r/20191006085646.5768-2-david@redhat.com Fixes: 2c2a5af6fed2 ("mm, memory_hotplug: add nid parameter to arch_remov= e_memory") Signed-off-by: Aneesh Kumar K.V Signed-off-by: David Hildenbrand Cc: Dan Williams Cc: Jason Gunthorpe Cc: Logan Gunthorpe Cc: Ira Weiny Cc: Damian Tometzki Cc: Alexander Duyck Cc: Alexander Potapenko Cc: Andy Lutomirski Cc: Anshuman Khandual Cc: Benjamin Herrenschmidt Cc: Borislav Petkov Cc: Catalin Marinas Cc: Christian Borntraeger Cc: Christophe Leroy Cc: Dave Hansen Cc: Fenghua Yu Cc: Gerald Schaefer Cc: Greg Kroah-Hartman Cc: Halil Pasic Cc: Heiko Carstens Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Jun Yao Cc: Mark Rutland Cc: Masahiro Yamada Cc: "Matthew Wilcox (Oracle)" Cc: Mel Gorman Cc: Michael Ellerman Cc: Michal Hocko Cc: Mike Rapoport Cc: Oscar Salvador Cc: Pankaj Gupta Cc: Paul Mackerras Cc: Pavel Tatashin Cc: Pavel Tatashin Cc: Peter Zijlstra Cc: Qian Cai Cc: Rich Felker Cc: Robin Murphy Cc: Steve Capper Cc: Thomas Gleixner Cc: Tom Lendacky Cc: Tony Luck Cc: Vasily Gorbik Cc: Vlastimil Babka Cc: Wei Yang Cc: Wei Yang Cc: Will Deacon Cc: Yoshinori Sato Cc: Yu Zhao Cc: [5.0+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: David Hildenbrand --- kernel/memremap.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/kernel/memremap.c b/kernel/memremap.c index 2ee2e672d5fc..1ec1f8fd97f5 100644 --- a/kernel/memremap.c +++ b/kernel/memremap.c @@ -120,6 +120,7 @@ static void devm_memremap_pages_release(void *data) struct device *dev =3D pgmap->dev; struct resource *res =3D &pgmap->res; resource_size_t align_start, align_size; + struct page *first_page; unsigned long pfn; int nid; =20 @@ -132,13 +133,16 @@ static void devm_memremap_pages_release(void *data) align_size =3D ALIGN(res->start + resource_size(res), SECTION_SIZE) - align_start; =20 - nid =3D page_to_nid(pfn_to_page(align_start >> PAGE_SHIFT)); + /* make sure to access a memmap that was actually initialized */ + first_page =3D pfn_to_page(pfn_first(pgmap)); + + nid =3D page_to_nid(first_page); =20 mem_hotplug_begin(); if (pgmap->type =3D=3D MEMORY_DEVICE_PRIVATE) { pfn =3D align_start >> PAGE_SHIFT; - __remove_pages(page_zone(pfn_to_page(pfn)), pfn, - align_size >> PAGE_SHIFT, NULL); + __remove_pages(page_zone(first_page), pfn, + align_size >> PAGE_SHIFT, NULL); } else { arch_remove_memory(nid, align_start, align_size, pgmap->altmap_valid ? &pgmap->altmap : NULL); --=20 2.24.1