linux/mm/page_alloc.c, branch v5.6

mm/memmap_init: update variable name in memmap_init_zone

2020-02-04T03:05:23Z

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 6): The third argument is actually number of pages. Change the variable name from size to nr_pages to indicate this better. No functional change in this patch. Link: http://lkml.kernel.org/r/20191006085646.5768-3-david@redhat.com Signed-off-by: Aneesh Kumar K.V Signed-off-by: David Hildenbrand Reviewed-by: Pankaj Gupta Reviewed-by: David Hildenbrand Cc: Michal Hocko Cc: "Matthew Wilcox (Oracle)" Cc: "Aneesh Kumar K.V" Cc: Pavel Tatashin Cc: Greg Kroah-Hartman Cc: Dan Williams Cc: Logan Gunthorpe Cc: Oscar Salvador Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: factor out next_present_section_nr()

2020-02-04T03:05:23Z

Let's move it to the header and use the shorter variant from mm/page_alloc.c (the original one will also check "__highest_present_section_nr + 1", which is not necessary). While at it, make the section_nr in next_pfn() const. In next_pfn(), we now return section_nr_to_pfn(-1) instead of -1 once we exceed __highest_present_section_nr, which doesn't make a difference in the caller as it is big enough (>= all sane end_pfn). Link: http://lkml.kernel.org/r/20200113144035.10848-3-david@redhat.com Signed-off-by: David Hildenbrand Acked-by: Kirill A. Shutemov Cc: Baoquan He Cc: Dan Williams Cc: "Jin, Zhi" Cc: "Kirill A. Shutemov" Cc: Mel Gorman Cc: Michal Hocko Cc: Michal Hocko Cc: Oscar Salvador Cc: Pavel Tatashin Cc: Vlastimil Babka Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/page_alloc: fix and rework pfn handling in memmap_init_zone()

2020-02-04T03:05:23Z

Let's update the pfn manually whenever we continue the loop. This makes the code easier to read but also less error prone (and we can directly fix one issue). When overlap_memmap_init() returns true, pfn is updated to "memblock_region_memory_end_pfn(r)". So it already points at the *next* pfn to process. Incrementing the pfn another time is wrong, we might leave one uninitialized. I spotted this by inspecting the code, so I have no idea if this is relevant in practise (with kernelcore=mirror). Link: http://lkml.kernel.org/r/20200113144035.10848-2-david@redhat.com Fixes: a9a9e77fbf27 ("mm: move mirrored memory specific code outside of memmap_init_zone") Signed-off-by: David Hildenbrand Acked-by: Kirill A. Shutemov Reviewed-by: Alexander Duyck Cc: Pavel Tatashin Cc: Michal Hocko Cc: Oscar Salvador Cc: Kirill A. Shutemov Cc: Baoquan He Cc: Dan Williams Cc: Vlastimil Babka Cc: Mel Gorman Cc: "Jin, Zhi" Cc: Michal Hocko Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/page_alloc.c: initialize memmap of unavailable memory directly

2020-02-04T03:05:23Z

Let's make sure that all memory holes are actually marked PageReserved(), that page_to_pfn() produces reliable results, and that these pages are not detected as "mmap" pages due to the mapcount. E.g., booting a x86-64 QEMU guest with 4160 MB: [ 0.010585] Early memory node ranges [ 0.010586] node 0: [mem 0x0000000000001000-0x000000000009efff] [ 0.010588] node 0: [mem 0x0000000000100000-0x00000000bffdefff] [ 0.010589] node 0: [mem 0x0000000100000000-0x0000000143ffffff] max_pfn is 0x144000. Before this change: [root@localhost ~]# ./page-types -r -a 0x144000, flags page-count MB symbolic-flags long-symbolic-flags 0x0000000000000800 16384 64 ___________M_______________________________ mmap total 16384 64 After this change: [root@localhost ~]# ./page-types -r -a 0x144000, flags page-count MB symbolic-flags long-symbolic-flags 0x0000000100000000 16384 64 ___________________________r_______________ reserved total 16384 64 IOW, especially the unavailable physical memory ("memory hole") in the last section would not get properly marked PageReserved() and is indicated to be "mmap" memory. Drop the trace of that function from include/linux/mm.h - nobody else needs it, and rename it accordingly. Note: The fake zone/node might not be covered by the zone/node span. This is not an urgent issue (for now, we had the same node/zone due to the zeroing). We'll need a clean way to mark memory holes (e.g., using a page type PageHole() if possible or a fake ZONE_INVALID) and eventually stop marking these memory holes PageReserved(). Link: http://lkml.kernel.org/r/20191211163201.17179-4-david@redhat.com Signed-off-by: David Hildenbrand Cc: Oscar Salvador Cc: Michal Hocko Cc: Dan Williams Cc: Alexey Dobriyan Cc: Bob Picco Cc: Daniel Jordan Cc: Michal Hocko Cc: Naoya Horiguchi Cc: Pavel Tatashin Cc: Stephen Rothwell Cc: Steven Sistare Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/page_alloc.c: fix uninitialized memmaps on a partially populated last section

2020-02-04T03:05:23Z

Patch series "mm: fix max_pfn not falling on section boundary", v2. Playing with different memory sizes for a x86-64 guest, I discovered that some memmaps (highest section if max_mem does not fall on the section boundary) are marked as being valid and online, but contain garbage. We have to properly initialize these memmaps. Looking at /proc/kpageflags and friends, I found some more issues, partially related to this. This patch (of 3): If max_pfn is not aligned to a section boundary, we can easily run into BUGs. This can e.g., be triggered on x86-64 under QEMU by specifying a memory size that is not a multiple of 128MB (e.g., 4097MB, but also 4160MB). I was told that on real HW, we can easily have this scenario (esp., one of the main reasons sub-section hotadd of devmem was added). The issue is, that we have a valid memmap (pfn_valid()) for the whole section, and the whole section will be marked "online". pfn_to_online_page() will succeed, but the memmap contains garbage. E.g., doing a "./page-types -r -a 0x144001" when QEMU was started with "-m 4160M" - (see tools/vm/page-types.c): [ 200.476376] BUG: unable to handle page fault for address: fffffffffffffffe [ 200.477500] #PF: supervisor read access in kernel mode [ 200.478334] #PF: error_code(0x0000) - not-present page [ 200.479076] PGD 59614067 P4D 59614067 PUD 59616067 PMD 0 [ 200.479557] Oops: 0000 [#4] SMP NOPTI [ 200.479875] CPU: 0 PID: 603 Comm: page-types Tainted: G D W 5.5.0-rc1-next-20191209 #93 [ 200.480646] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.0-59-gc9ba5276e321-prebuilt.qemu4 [ 200.481648] RIP: 0010:stable_page_flags+0x4d/0x410 [ 200.482061] Code: f3 ff 41 89 c0 48 b8 00 00 00 00 01 00 00 00 45 84 c0 0f 85 cd 02 00 00 48 8b 53 08 48 8b 2b 48f [ 200.483644] RSP: 0018:ffffb139401cbe60 EFLAGS: 00010202 [ 200.484091] RAX: fffffffffffffffe RBX: fffffbeec5100040 RCX: 0000000000000000 [ 200.484697] RDX: 0000000000000001 RSI: ffffffff9535c7cd RDI: 0000000000000246 [ 200.485313] RBP: ffffffffffffffff R08: 0000000000000000 R09: 0000000000000000 [ 200.485917] R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000144001 [ 200.486523] R13: 00007ffd6ba55f48 R14: 00007ffd6ba55f40 R15: ffffb139401cbf08 [ 200.487130] FS: 00007f68df717580(0000) GS:ffff9ec77fa00000(0000) knlGS:0000000000000000 [ 200.487804] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 200.488295] CR2: fffffffffffffffe CR3: 0000000135d48000 CR4: 00000000000006f0 [ 200.488897] Call Trace: [ 200.489115] kpageflags_read+0xe9/0x140 [ 200.489447] proc_reg_read+0x3c/0x60 [ 200.489755] vfs_read+0xc2/0x170 [ 200.490037] ksys_pread64+0x65/0xa0 [ 200.490352] do_syscall_64+0x5c/0xa0 [ 200.490665] entry_SYSCALL_64_after_hwframe+0x49/0xbe But it can be triggered much easier via "cat /proc/kpageflags > /dev/null" after cold/hot plugging a DIMM to such a system: [root@localhost ~]# cat /proc/kpageflags > /dev/null [ 111.517275] BUG: unable to handle page fault for address: fffffffffffffffe [ 111.517907] #PF: supervisor read access in kernel mode [ 111.518333] #PF: error_code(0x0000) - not-present page [ 111.518771] PGD a240e067 P4D a240e067 PUD a2410067 PMD 0 This patch fixes that by at least zero-ing out that memmap (so e.g., page_to_pfn() will not crash). Commit 907ec5fca3dc ("mm: zero remaining unavailable struct pages") tried to fix a similar issue, but forgot to consider this special case. After this patch, there are still problems to solve. E.g., not all of these pages falling into a memory hole will actually get initialized later and set PageReserved - they are only zeroed out - but at least the immediate crashes are gone. A follow-up patch will take care of this. Link: http://lkml.kernel.org/r/20191211163201.17179-2-david@redhat.com Fixes: f7f99100d8d9 ("mm: stop zeroing memory during allocation in vmemmap") Signed-off-by: David Hildenbrand Tested-by: Daniel Jordan Cc: Naoya Horiguchi Cc: Pavel Tatashin Cc: Andrew Morton Cc: Steven Sistare Cc: Michal Hocko Cc: Daniel Jordan Cc: Bob Picco Cc: Oscar Salvador Cc: Alexey Dobriyan Cc: Dan Williams Cc: Michal Hocko Cc: Stephen Rothwell Cc: [4.15+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/page_isolation: fix potential warning from user

2020-01-31T18:30:39Z

It makes sense to call the WARN_ON_ONCE(zone_idx(zone) == ZONE_MOVABLE) from start_isolate_page_range(), but should avoid triggering it from userspace, i.e, from is_mem_section_removable() because it could crash the system by a non-root user if warn_on_panic is set. While at it, simplify the code a bit by removing an unnecessary jump label. Link: http://lkml.kernel.org/r/20200120163915.1469-1-cai@lca.pw Signed-off-by: Qian Cai Suggested-by: Michal Hocko Acked-by: Michal Hocko Reviewed-by: David Hildenbrand Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/hotplug: silence a lockdep splat with printk()

2020-01-31T18:30:39Z

It is not that hard to trigger lockdep splats by calling printk from under zone->lock. Most of them are false positives caused by lock chains introduced early in the boot process and they do not cause any real problems (although most of the early boot lock dependencies could happen after boot as well). There are some console drivers which do allocate from the printk context as well and those should be fixed. In any case, false positives are not that trivial to workaround and it is far from optimal to lose lockdep functionality for something that is a non-issue. So change has_unmovable_pages() so that it no longer calls dump_page() itself - instead it returns a "struct page *" of the unmovable page back to the caller so that in the case of a has_unmovable_pages() failure, the caller can call dump_page() after releasing zone->lock. Also, make dump_page() is able to report a CMA page as well, so the reason string from has_unmovable_pages() can be removed. Even though has_unmovable_pages doesn't hold any reference to the returned page this should be reasonably safe for the purpose of reporting the page (dump_page) because it cannot be hotremoved in the context of memory unplug. The state of the page might change but that is the case even with the existing code as zone->lock only plays role for free pages. While at it, remove a similar but unnecessary debug-only printk() as well. A sample of one of those lockdep splats is, WARNING: possible circular locking dependency detected ------------------------------------------------------ test.sh/8653 is trying to acquire lock: ffffffff865a4460 (console_owner){-.-.}, at: console_unlock+0x207/0x750 but task is already holding lock: ffff88883fff3c58 (&(&zone->lock)->rlock){-.-.}, at: __offline_isolated_pages+0x179/0x3e0 which lock already depends on the new lock. the existing dependency chain (in reverse order) is: -> #3 (&(&zone->lock)->rlock){-.-.}: __lock_acquire+0x5b3/0xb40 lock_acquire+0x126/0x280 _raw_spin_lock+0x2f/0x40 rmqueue_bulk.constprop.21+0xb6/0x1160 get_page_from_freelist+0x898/0x22c0 __alloc_pages_nodemask+0x2f3/0x1cd0 alloc_pages_current+0x9c/0x110 allocate_slab+0x4c6/0x19c0 new_slab+0x46/0x70 ___slab_alloc+0x58b/0x960 __slab_alloc+0x43/0x70 __kmalloc+0x3ad/0x4b0 __tty_buffer_request_room+0x100/0x250 tty_insert_flip_string_fixed_flag+0x67/0x110 pty_write+0xa2/0xf0 n_tty_write+0x36b/0x7b0 tty_write+0x284/0x4c0 __vfs_write+0x50/0xa0 vfs_write+0x105/0x290 redirected_tty_write+0x6a/0xc0 do_iter_write+0x248/0x2a0 vfs_writev+0x106/0x1e0 do_writev+0xd4/0x180 __x64_sys_writev+0x45/0x50 do_syscall_64+0xcc/0x76c entry_SYSCALL_64_after_hwframe+0x49/0xbe -> #2 (&(&port->lock)->rlock){-.-.}: __lock_acquire+0x5b3/0xb40 lock_acquire+0x126/0x280 _raw_spin_lock_irqsave+0x3a/0x50 tty_port_tty_get+0x20/0x60 tty_port_default_wakeup+0xf/0x30 tty_port_tty_wakeup+0x39/0x40 uart_write_wakeup+0x2a/0x40 serial8250_tx_chars+0x22e/0x440 serial8250_handle_irq.part.8+0x14a/0x170 serial8250_default_handle_irq+0x5c/0x90 serial8250_interrupt+0xa6/0x130 __handle_irq_event_percpu+0x78/0x4f0 handle_irq_event_percpu+0x70/0x100 handle_irq_event+0x5a/0x8b handle_edge_irq+0x117/0x370 do_IRQ+0x9e/0x1e0 ret_from_intr+0x0/0x2a cpuidle_enter_state+0x156/0x8e0 cpuidle_enter+0x41/0x70 call_cpuidle+0x5e/0x90 do_idle+0x333/0x370 cpu_startup_entry+0x1d/0x1f start_secondary+0x290/0x330 secondary_startup_64+0xb6/0xc0 -> #1 (&port_lock_key){-.-.}: __lock_acquire+0x5b3/0xb40 lock_acquire+0x126/0x280 _raw_spin_lock_irqsave+0x3a/0x50 serial8250_console_write+0x3e4/0x450 univ8250_console_write+0x4b/0x60 console_unlock+0x501/0x750 vprintk_emit+0x10d/0x340 vprintk_default+0x1f/0x30 vprintk_func+0x44/0xd4 printk+0x9f/0xc5 -> #0 (console_owner){-.-.}: check_prev_add+0x107/0xea0 validate_chain+0x8fc/0x1200 __lock_acquire+0x5b3/0xb40 lock_acquire+0x126/0x280 console_unlock+0x269/0x750 vprintk_emit+0x10d/0x340 vprintk_default+0x1f/0x30 vprintk_func+0x44/0xd4 printk+0x9f/0xc5 __offline_isolated_pages.cold.52+0x2f/0x30a offline_isolated_pages_cb+0x17/0x30 walk_system_ram_range+0xda/0x160 __offline_pages+0x79c/0xa10 offline_pages+0x11/0x20 memory_subsys_offline+0x7e/0xc0 device_offline+0xd5/0x110 state_store+0xc6/0xe0 dev_attr_store+0x3f/0x60 sysfs_kf_write+0x89/0xb0 kernfs_fop_write+0x188/0x240 __vfs_write+0x50/0xa0 vfs_write+0x105/0x290 ksys_write+0xc6/0x160 __x64_sys_write+0x43/0x50 do_syscall_64+0xcc/0x76c entry_SYSCALL_64_after_hwframe+0x49/0xbe other info that might help us debug this: Chain exists of: console_owner --> &(&port->lock)->rlock --> &(&zone->lock)->rlock Possible unsafe locking scenario: CPU0 CPU1 ---- ---- lock(&(&zone->lock)->rlock); lock(&(&port->lock)->rlock); lock(&(&zone->lock)->rlock); lock(console_owner); *** DEADLOCK *** 9 locks held by test.sh/8653: #0: ffff88839ba7d408 (sb_writers#4){.+.+}, at: vfs_write+0x25f/0x290 #1: ffff888277618880 (&of->mutex){+.+.}, at: kernfs_fop_write+0x128/0x240 #2: ffff8898131fc218 (kn->count#115){.+.+}, at: kernfs_fop_write+0x138/0x240 #3: ffffffff86962a80 (device_hotplug_lock){+.+.}, at: lock_device_hotplug_sysfs+0x16/0x50 #4: ffff8884374f4990 (&dev->mutex){....}, at: device_offline+0x70/0x110 #5: ffffffff86515250 (cpu_hotplug_lock.rw_sem){++++}, at: __offline_pages+0xbf/0xa10 #6: ffffffff867405f0 (mem_hotplug_lock.rw_sem){++++}, at: percpu_down_write+0x87/0x2f0 #7: ffff88883fff3c58 (&(&zone->lock)->rlock){-.-.}, at: __offline_isolated_pages+0x179/0x3e0 #8: ffffffff865a4920 (console_lock){+.+.}, at: vprintk_emit+0x100/0x340 stack backtrace: Hardware name: HPE ProLiant DL560 Gen10/ProLiant DL560 Gen10, BIOS U34 05/21/2019 Call Trace: dump_stack+0x86/0xca print_circular_bug.cold.31+0x243/0x26e check_noncircular+0x29e/0x2e0 check_prev_add+0x107/0xea0 validate_chain+0x8fc/0x1200 __lock_acquire+0x5b3/0xb40 lock_acquire+0x126/0x280 console_unlock+0x269/0x750 vprintk_emit+0x10d/0x340 vprintk_default+0x1f/0x30 vprintk_func+0x44/0xd4 printk+0x9f/0xc5 __offline_isolated_pages.cold.52+0x2f/0x30a offline_isolated_pages_cb+0x17/0x30 walk_system_ram_range+0xda/0x160 __offline_pages+0x79c/0xa10 offline_pages+0x11/0x20 memory_subsys_offline+0x7e/0xc0 device_offline+0xd5/0x110 state_store+0xc6/0xe0 dev_attr_store+0x3f/0x60 sysfs_kf_write+0x89/0xb0 kernfs_fop_write+0x188/0x240 __vfs_write+0x50/0xa0 vfs_write+0x105/0x290 ksys_write+0xc6/0x160 __x64_sys_write+0x43/0x50 do_syscall_64+0xcc/0x76c entry_SYSCALL_64_after_hwframe+0x49/0xbe Link: http://lkml.kernel.org/r/20200117181200.20299-1-cai@lca.pw Signed-off-by: Qian Cai Reviewed-by: David Hildenbrand Cc: Michal Hocko Cc: Sergey Senozhatsky Cc: Petr Mladek Cc: Steven Rostedt (VMware) Cc: Peter Zijlstra Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm: remove "count" parameter from has_unmovable_pages()

2020-01-31T18:30:38Z

Now that the memory isolate notifier is gone, the parameter is always 0. Drop it and cleanup has_unmovable_pages(). Link: http://lkml.kernel.org/r/20191114131911.11783-3-david@redhat.com Signed-off-by: David Hildenbrand Acked-by: Michal Hocko Cc: Oscar Salvador Cc: Anshuman Khandual Cc: Qian Cai Cc: Pingfan Liu Cc: Stephen Rothwell Cc: Dan Williams Cc: Pavel Tatashin Cc: Vlastimil Babka Cc: Mel Gorman Cc: Mike Rapoport Cc: Wei Yang Cc: Alexander Duyck Cc: Alexander Potapenko Cc: Arun KS Cc: Michael Ellerman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm/page_alloc: skip non present sections on zone initialization

2020-01-31T18:30:38Z

memmap_init_zone() can be called on the ranges with holes during the boot. It will skip any non-valid PFNs one-by-one. It works fine as long as holes are not too big. But huge holes in the memory map causes a problem. It takes over 20 seconds to walk 32TiB hole. x86-64 with 5-level paging allows for much larger holes in the memory map which would practically hang the system. Deferred struct page init doesn't help here. It only works on the present ranges. Skipping non-present sections would fix the issue. Link: http://lkml.kernel.org/r/20191230093828.24613-1-kirill.shutemov@linux.intel.com Signed-off-by: Kirill A. Shutemov Reviewed-by: Baoquan He Acked-by: Michal Hocko Cc: Dan Williams Cc: Vlastimil Babka Cc: Mel Gorman Cc: "Jin, Zhi" Cc: David Hildenbrand Cc: Michal Hocko Cc: Oscar Salvador Cc: Pavel Tatashin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds

mm, debug_pagealloc: don't rely on static keys too early

2020-01-14T02:19:02Z

Commit 96a2b03f281d ("mm, debug_pagelloc: use static keys to enable debugging") has introduced a static key to reduce overhead when debug_pagealloc is compiled in but not enabled. It relied on the assumption that jump_label_init() is called before parse_early_param() as in start_kernel(), so when the "debug_pagealloc=on" option is parsed, it is safe to enable the static key. However, it turns out multiple architectures call parse_early_param() earlier from their setup_arch(). x86 also calls jump_label_init() even earlier, so no issue was found while testing the commit, but same is not true for e.g. ppc64 and s390 where the kernel would not boot with debug_pagealloc=on as found by our QA. To fix this without tricky changes to init code of multiple architectures, this patch partially reverts the static key conversion from 96a2b03f281d. Init-time and non-fastpath calls (such as in arch code) of debug_pagealloc_enabled() will again test a simple bool variable. Fastpath mm code is converted to a new debug_pagealloc_enabled_static() variant that relies on the static key, which is enabled in a well-defined point in mm_init() where it's guaranteed that jump_label_init() has been called, regardless of architecture. [sfr@canb.auug.org.au: export _debug_pagealloc_enabled_early] Link: http://lkml.kernel.org/r/20200106164944.063ac07b@canb.auug.org.au Link: http://lkml.kernel.org/r/20191219130612.23171-1-vbabka@suse.cz Fixes: 96a2b03f281d ("mm, debug_pagelloc: use static keys to enable debugging") Signed-off-by: Vlastimil Babka Signed-off-by: Stephen Rothwell Cc: Joonsoo Kim Cc: "Kirill A. Shutemov" Cc: Michal Hocko Cc: Vlastimil Babka Cc: Matthew Wilcox Cc: Mel Gorman Cc: Peter Zijlstra Cc: Borislav Petkov Cc: Qian Cai Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds