Has this been properly reviewed? I do not see any Acks nor Reviewed-bys.
On Fri 18-10-19 20:19:39, Andrew Morton wrote:
From: "Aneesh Kumar K.V" aneesh.kumar@linux.ibm.com Subject: mm/memunmap: don't access uninitialized memmap in memunmap_pages()
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:
[ 81.356173] 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 = 3669, comm = ndctl kernel BUG at include/linux/mm.h:1107! [c000000274087ba0] c0000000009e3500 devm_action_release+0x30/0x50 [c000000274087bc0] c0000000009e4758 release_nodes+0x268/0x2d0 [c000000274087c30] c0000000009dd144 device_release_driver_internal+0x174/0x240 [c000000274087c70] c0000000009d9dfc unbind_store+0x13c/0x190 [c000000274087cb0] c0000000009d8a24 drv_attr_store+0x44/0x60 [c000000274087cd0] c0000000005a7470 sysfs_kf_write+0x70/0xa0 [c000000274087d10] c0000000005a5cac kernfs_fop_write+0x1ac/0x290 [c000000274087d60] c0000000004be45c __vfs_write+0x3c/0x70 [c000000274087d80] c0000000004c26e4 vfs_write+0xe4/0x200 [c000000274087dd0] c0000000004c2a6c ksys_write+0x7c/0x140 [c000000274087e20] c00000000000bbd0 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_remove_memory") Signed-off-by: Aneesh Kumar K.V aneesh.kumar@linux.ibm.com Signed-off-by: David Hildenbrand david@redhat.com Cc: Dan Williams dan.j.williams@intel.com Cc: Jason Gunthorpe jgg@ziepe.ca Cc: Logan Gunthorpe logang@deltatee.com Cc: Ira Weiny ira.weiny@intel.com Cc: Damian Tometzki damian.tometzki@gmail.com Cc: Alexander Duyck alexander.h.duyck@linux.intel.com Cc: Alexander Potapenko glider@google.com Cc: Andy Lutomirski luto@kernel.org Cc: Anshuman Khandual anshuman.khandual@arm.com Cc: Benjamin Herrenschmidt benh@kernel.crashing.org Cc: Borislav Petkov bp@alien8.de Cc: Catalin Marinas catalin.marinas@arm.com Cc: Christian Borntraeger borntraeger@de.ibm.com Cc: Christophe Leroy christophe.leroy@c-s.fr Cc: Dave Hansen dave.hansen@linux.intel.com Cc: Fenghua Yu fenghua.yu@intel.com Cc: Gerald Schaefer gerald.schaefer@de.ibm.com Cc: Greg Kroah-Hartman gregkh@linuxfoundation.org Cc: Halil Pasic pasic@linux.ibm.com Cc: Heiko Carstens heiko.carstens@de.ibm.com Cc: "H. Peter Anvin" hpa@zytor.com Cc: Ingo Molnar mingo@redhat.com Cc: Jun Yao yaojun8558363@gmail.com Cc: Mark Rutland mark.rutland@arm.com Cc: Masahiro Yamada yamada.masahiro@socionext.com Cc: "Matthew Wilcox (Oracle)" willy@infradead.org Cc: Mel Gorman mgorman@techsingularity.net Cc: Michael Ellerman mpe@ellerman.id.au Cc: Michal Hocko mhocko@suse.com Cc: Mike Rapoport rppt@linux.ibm.com Cc: Oscar Salvador osalvador@suse.de Cc: Pankaj Gupta pagupta@redhat.com Cc: Paul Mackerras paulus@samba.org Cc: Pavel Tatashin pasha.tatashin@soleen.com Cc: Pavel Tatashin pavel.tatashin@microsoft.com Cc: Peter Zijlstra peterz@infradead.org Cc: Qian Cai cai@lca.pw Cc: Rich Felker dalias@libc.org Cc: Robin Murphy robin.murphy@arm.com Cc: Steve Capper steve.capper@arm.com Cc: Thomas Gleixner tglx@linutronix.de Cc: Tom Lendacky thomas.lendacky@amd.com Cc: Tony Luck tony.luck@intel.com Cc: Vasily Gorbik gor@linux.ibm.com Cc: Vlastimil Babka vbabka@suse.cz Cc: Wei Yang richard.weiyang@gmail.com Cc: Wei Yang richardw.yang@linux.intel.com Cc: Will Deacon will@kernel.org Cc: Yoshinori Sato ysato@users.sourceforge.jp Cc: Yu Zhao yuzhao@google.com Cc: stable@vger.kernel.org [5.0+] Signed-off-by: Andrew Morton akpm@linux-foundation.org
mm/memremap.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-)
--- a/mm/memremap.c~mm-memunmap-dont-access-uninitialized-memmap-in-memunmap_pages +++ a/mm/memremap.c @@ -103,6 +103,7 @@ static void dev_pagemap_cleanup(struct d void memunmap_pages(struct dev_pagemap *pgmap) { struct resource *res = &pgmap->res;
- struct page *first_page; unsigned long pfn; int nid;
@@ -111,14 +112,16 @@ void memunmap_pages(struct dev_pagemap * put_page(pfn_to_page(pfn)); dev_pagemap_cleanup(pgmap);
- /* make sure to access a memmap that was actually initialized */
- first_page = pfn_to_page(pfn_first(pgmap));
- /* pages are dead and unused, undo the arch mapping */
- nid = page_to_nid(pfn_to_page(PHYS_PFN(res->start)));
- nid = page_to_nid(first_page);
mem_hotplug_begin(); if (pgmap->type == MEMORY_DEVICE_PRIVATE) {
pfn = PHYS_PFN(res->start);__remove_pages(page_zone(pfn_to_page(pfn)), pfn,PHYS_PFN(resource_size(res)), NULL);
__remove_pages(page_zone(first_page), PHYS_PFN(res->start),PHYS_PFN(resource_size(res)), NULL);_