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9803fc4f4a
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Qian Cai 9803fc4f4a mm/hotplug: invalid PFNs from pfn_to_online_page() 
[ Upstream commit b13bc35193 ]

On an arm64 ThunderX2 server, the first kmemleak scan would crash [1]
with CONFIG_DEBUG_VM_PGFLAGS=y due to page_to_nid() found a pfn that is
not directly mapped (MEMBLOCK_NOMAP).  Hence, the page->flags is
uninitialized.

This is due to the commit 9f1eb38e0e ("mm, kmemleak: little
optimization while scanning") starts to use pfn_to_online_page() instead
of pfn_valid().  However, in the CONFIG_MEMORY_HOTPLUG=y case,
pfn_to_online_page() does not call memblock_is_map_memory() while
pfn_valid() does.

Historically, the commit 68709f4538 ("arm64: only consider memblocks
with NOMAP cleared for linear mapping") causes pages marked as nomap
being no long reassigned to the new zone in memmap_init_zone() by
calling __init_single_page().

Since the commit 2d070eab2e ("mm: consider zone which is not fully
populated to have holes") introduced pfn_to_online_page() and was
designed to return a valid pfn only, but it is clearly broken on arm64.

Therefore, let pfn_to_online_page() call pfn_valid_within(), so it can
handle nomap thanks to the commit f52bb98f5a ("arm64: mm: always
enable CONFIG_HOLES_IN_ZONE"), while it will be optimized away on
architectures where have no HOLES_IN_ZONE.

[1]
  Unable to handle kernel NULL pointer dereference at virtual address 0000000000000006
  Mem abort info:
    ESR = 0x96000005
    Exception class = DABT (current EL), IL = 32 bits
    SET = 0, FnV = 0
    EA = 0, S1PTW = 0
  Data abort info:
    ISV = 0, ISS = 0x00000005
    CM = 0, WnR = 0
  Internal error: Oops: 96000005 [#1] SMP
  CPU: 60 PID: 1408 Comm: kmemleak Not tainted 5.0.0-rc2+ #8
  pstate: 60400009 (nZCv daif +PAN -UAO)
  pc : page_mapping+0x24/0x144
  lr : __dump_page+0x34/0x3dc
  sp : ffff00003a5cfd10
  x29: ffff00003a5cfd10 x28: 000000000000802f
  x27: 0000000000000000 x26: 0000000000277d00
  x25: ffff000010791f56 x24: ffff7fe000000000
  x23: ffff000010772f8b x22: ffff00001125f670
  x21: ffff000011311000 x20: ffff000010772f8b
  x19: fffffffffffffffe x18: 0000000000000000
  x17: 0000000000000000 x16: 0000000000000000
  x15: 0000000000000000 x14: ffff802698b19600
  x13: ffff802698b1a200 x12: ffff802698b16f00
  x11: ffff802698b1a400 x10: 0000000000001400
  x9 : 0000000000000001 x8 : ffff00001121a000
  x7 : 0000000000000000 x6 : ffff0000102c53b8
  x5 : 0000000000000000 x4 : 0000000000000003
  x3 : 0000000000000100 x2 : 0000000000000000
  x1 : ffff000010772f8b x0 : ffffffffffffffff
  Process kmemleak (pid: 1408, stack limit = 0x(____ptrval____))
  Call trace:
   page_mapping+0x24/0x144
   __dump_page+0x34/0x3dc
   dump_page+0x28/0x4c
   kmemleak_scan+0x4ac/0x680
   kmemleak_scan_thread+0xb4/0xdc
   kthread+0x12c/0x13c
   ret_from_fork+0x10/0x18
  Code: d503201f f9400660 36000040 d1000413 (f9400661)
  ---[ end trace 4d4bd7f573490c8e ]---
  Kernel panic - not syncing: Fatal exception
  SMP: stopping secondary CPUs
  Kernel Offset: disabled
  CPU features: 0x002,20000c38
  Memory Limit: none
  ---[ end Kernel panic - not syncing: Fatal exception ]---

Link: http://lkml.kernel.org/r/20190122132916.28360-1-cai@lca.pw
Fixes: 9f1eb38e0e ("mm, kmemleak: little optimization while scanning")
Signed-off-by: Qian Cai <cai@lca.pw>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-12-05 09:21:08 +01:00
arch um: Make GCOV depend on !KCOV 2019-12-05 09:20:52 +01:00
block block: call rq_qos_exit() after queue is frozen 2019-12-01 09:17:06 +01:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: user - support incremental algorithm dumps 2019-12-05 09:20:04 +01:00
Documentation HID: doc: fix wrong data structure reference for UHID_OUTPUT 2019-12-05 09:20:36 +01:00
drivers sfc: suppress duplicate nvmem partition types in efx_ef10_mtd_probe 2019-12-05 09:21:07 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs ocfs2: clear journal dirty flag after shutdown journal 2019-12-05 09:20:56 +01:00
include mm/hotplug: invalid PFNs from pfn_to_online_page() 2019-12-05 09:21:08 +01:00
init fork: fix some -Wmissing-prototypes warnings 2019-12-05 09:21:04 +01:00
ipc ipc/mqueue.c: only perform resource calculation if user valid 2019-08-06 19:06:52 +02:00
kernel fork: fix some -Wmissing-prototypes warnings 2019-12-05 09:21:04 +01:00
lib lib/genalloc.c: include vmalloc.h 2019-12-05 09:21:05 +01:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm/page_alloc.c: deduplicate __memblock_free_early() and memblock_free() 2019-12-05 09:20:58 +01:00
net net/smc: don't wait for send buffer space when data was already sent 2019-12-05 09:21:08 +01:00
samples vfio-mdev/samples: Use u8 instead of char for handle functions 2019-12-05 09:20:28 +01:00
scripts scripts/gdb: fix debugging modules compiled with hot/cold partitioning 2019-12-05 09:19:44 +01:00
security ima: fix freeing ongoing ahash_request 2019-10-11 18:21:11 +02:00
sound ASoC: stm32: sai: add restriction on mmap support 2019-12-05 09:19:44 +01:00
tools tools/vm/page-types.c: fix "kpagecount returned fewer pages than expected" failures 2019-12-05 09:20:59 +01:00
usr kbuild: clean compressed initramfs image 2019-10-07 18:57:16 +02:00
virt KVM: MMU: Do not treat ZONE_DEVICE pages as being reserved 2019-12-01 09:17:35 +01:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS USB: rio500: Remove Rio 500 kernel driver 2019-10-17 13:44:47 -07:00
Makefile Linux 4.19.87 2019-12-01 09:17:47 +01:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.