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" <[email protected]> > 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). > > [[email protected]: minimze code changes, rephrase description] > Link: http://lkml.kernel.org/r/[email protected] > Fixes: 2c2a5af6fed2 ("mm, memory_hotplug: add nid parameter to > arch_remove_memory") > Signed-off-by: Aneesh Kumar K.V <[email protected]> > Signed-off-by: David Hildenbrand <[email protected]> > Cc: Dan Williams <[email protected]> > Cc: Jason Gunthorpe <[email protected]> > Cc: Logan Gunthorpe <[email protected]> > Cc: Ira Weiny <[email protected]> > Cc: Damian Tometzki <[email protected]> > Cc: Alexander Duyck <[email protected]> > Cc: Alexander Potapenko <[email protected]> > Cc: Andy Lutomirski <[email protected]> > Cc: Anshuman Khandual <[email protected]> > Cc: Benjamin Herrenschmidt <[email protected]> > Cc: Borislav Petkov <[email protected]> > Cc: Catalin Marinas <[email protected]> > Cc: Christian Borntraeger <[email protected]> > Cc: Christophe Leroy <[email protected]> > Cc: Dave Hansen <[email protected]> > Cc: Fenghua Yu <[email protected]> > Cc: Gerald Schaefer <[email protected]> > Cc: Greg Kroah-Hartman <[email protected]> > Cc: Halil Pasic <[email protected]> > Cc: Heiko Carstens <[email protected]> > Cc: "H. Peter Anvin" <[email protected]> > Cc: Ingo Molnar <[email protected]> > Cc: Jun Yao <[email protected]> > Cc: Mark Rutland <[email protected]> > Cc: Masahiro Yamada <[email protected]> > Cc: "Matthew Wilcox (Oracle)" <[email protected]> > Cc: Mel Gorman <[email protected]> > Cc: Michael Ellerman <[email protected]> > Cc: Michal Hocko <[email protected]> > Cc: Mike Rapoport <[email protected]> > Cc: Oscar Salvador <[email protected]> > Cc: Pankaj Gupta <[email protected]> > Cc: Paul Mackerras <[email protected]> > Cc: Pavel Tatashin <[email protected]> > Cc: Pavel Tatashin <[email protected]> > Cc: Peter Zijlstra <[email protected]> > Cc: Qian Cai <[email protected]> > Cc: Rich Felker <[email protected]> > Cc: Robin Murphy <[email protected]> > Cc: Steve Capper <[email protected]> > Cc: Thomas Gleixner <[email protected]> > Cc: Tom Lendacky <[email protected]> > Cc: Tony Luck <[email protected]> > Cc: Vasily Gorbik <[email protected]> > Cc: Vlastimil Babka <[email protected]> > Cc: Wei Yang <[email protected]> > Cc: Wei Yang <[email protected]> > Cc: Will Deacon <[email protected]> > Cc: Yoshinori Sato <[email protected]> > Cc: Yu Zhao <[email protected]> > Cc: <[email protected]> [5.0+] > Signed-off-by: Andrew Morton <[email protected]> > --- > > 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); > } else { > arch_remove_memory(nid, res->start, resource_size(res), > pgmap_altmap(pgmap)); > _
-- Michal Hocko SUSE Labs
