Skip to content

K
Kernel

openeuler / Kernel
大约 2 年 前同步成功

通知 8
Star 0
Fork 0
K
Kernel
切换分支/标签
  1. 01 12月, 2022 1 次提交
    • H
      mm,thp,rmap: simplify compound page mapcount handling · cb67f428
      由 Hugh Dickins 提交于 
      Compound page (folio) mapcount calculations have been different for anon
and file (or shmem) THPs, and involved the obscure PageDoubleMap flag. 
And each huge mapping and unmapping of a file (or shmem) THP involved
atomically incrementing and decrementing the mapcount of every subpage of
that huge page, dirtying many struct page cachelines.

Add subpages_mapcount field to the struct folio and first tail page, so
that the total of subpage mapcounts is available in one place near the
head: then page_mapcount() and total_mapcount() and page_mapped(), and
their folio equivalents, are so quick that anon and file and hugetlb don't
need to be optimized differently.  Delete the unloved PageDoubleMap.

page_add and page_remove rmap functions must now maintain the
subpages_mapcount as well as the subpage _mapcount, when dealing with pte
mappings of huge pages; and correct maintenance of NR_ANON_MAPPED and
NR_FILE_MAPPED statistics still needs reading through the subpages, using
nr_subpages_unmapped() - but only when first or last pmd mapping finds
subpages_mapcount raised (double-map case, not the common case).

But are those counts (used to decide when to split an anon THP, and in
vmscan's pagecache_reclaimable heuristic) correctly maintained?  Not
quite: since page_remove_rmap() (and also split_huge_pmd()) is often
called without page lock, there can be races when a subpage pte mapcount
0<->1 while compound pmd mapcount 0<->1 is scanning - races which the
previous implementation had prevented.  The statistics might become
inaccurate, and even drift down until they underflow through 0.  That is
not good enough, but is better dealt with in a followup patch.

Update a few comments on first and second tail page overlaid fields. 
hugepage_add_new_anon_rmap() has to "increment" compound_mapcount, but
subpages_mapcount and compound_pincount are already correctly at 0, so
delete its reinitialization of compound_pincount.

A simple 100 X munmap(mmap(2GB, MAP_SHARED|MAP_POPULATE, tmpfs), 2GB) took
18 seconds on small pages, and used to take 1 second on huge pages, but
now takes 119 milliseconds on huge pages.  Mapping by pmds a second time
used to take 860ms and now takes 92ms; mapping by pmds after mapping by
ptes (when the scan is needed) used to take 870ms and now takes 495ms. 
But there might be some benchmarks which would show a slowdown, because
tail struct pages now fall out of cache until final freeing checks them.

Link: https://lkml.kernel.org/r/47ad693-717-79c8-e1ba-46c3a6602e48@google.comSigned-off-by: NHugh Dickins <hughd@google.com>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Mina Almasry <almasrymina@google.com>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Naoya Horiguchi <naoya.horiguchi@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
      cb67f428
  3. 27 9月, 2022 2 次提交
  5. 25 3月, 2022 1 次提交
  7. 22 3月, 2022 2 次提交
  9. 15 1月, 2022 1 次提交
  11. 07 11月, 2021 1 次提交
  13. 27 10月, 2021 1 次提交
  15. 09 10月, 2021 1 次提交
    • E
      coredump: Limit coredumps to a single thread group · 0258b5fd
      由 Eric W. Biederman 提交于 
      Today when a signal is delivered with a handler of SIG_DFL whose
default behavior is to generate a core dump not only that process but
every process that shares the mm is killed.

In the case of vfork this looks like a real world problem.  Consider
the following well defined sequence.

	if (vfork() == 0) {
		execve(...);
		_exit(EXIT_FAILURE);
	}

If a signal that generates a core dump is received after vfork but
before the execve changes the mm the process that called vfork will
also be killed (as the mm is shared).

Similarly if the execve fails after the point of no return the kernel
delivers SIGSEGV which will kill both the exec'ing process and because
the mm is shared the process that called vfork as well.

As far as I can tell this behavior is a violation of people's
reasonable expectations, POSIX, and is unnecessarily fragile when the
system is low on memory.

Solve this by making a userspace visible change to only kill a single
process/thread group.  This is possible because Jann Horn recently
modified[1] the coredump code so that the mm can safely be modified
while the coredump is happening.  With LinuxThreads long gone I don't
expect anyone to have a notice this behavior change in practice.

To accomplish this move the core_state pointer from mm_struct to
signal_struct, which allows different thread groups to coredump
simultatenously.

In zap_threads remove the work to kill anything except for the current
thread group.

v2: Remove core_state from the VM_BUG_ON_MM print to fix
    compile failure when CONFIG_DEBUG_VM is enabled.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>

[1] a07279c9 ("binfmt_elf, binfmt_elf_fdpic: use a VMA list snapshot")
Fixes: d89f3847def4 ("[PATCH] thread-aware coredumps, 2.5.43-C3")
History-tree: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Link: https://lkml.kernel.org/r/87y27mvnke.fsf@disp2133
Link: https://lkml.kernel.org/r/20211007144701.67592574@canb.auug.org.auReviewed-by: NKees Cook <keescook@chromium.org>
Signed-off-by: N"Eric W. Biederman" <ebiederm@xmission.com>
      0258b5fd
  17. 25 9月, 2021 2 次提交
  19. 30 6月, 2021 2 次提交
  21. 25 2月, 2021 1 次提交
  23. 03 12月, 2020 1 次提交
    • R
      mm: memcontrol: Use helpers to read page's memcg data · bcfe06bf
      由 Roman Gushchin 提交于 
      Patch series "mm: allow mapping accounted kernel pages to userspace", v6.

Currently a non-slab kernel page which has been charged to a memory cgroup
can't be mapped to userspace.  The underlying reason is simple: PageKmemcg
flag is defined as a page type (like buddy, offline, etc), so it takes a
bit from a page->mapped counter.  Pages with a type set can't be mapped to
userspace.

But in general the kmemcg flag has nothing to do with mapping to
userspace.  It only means that the page has been accounted by the page
allocator, so it has to be properly uncharged on release.

Some bpf maps are mapping the vmalloc-based memory to userspace, and their
memory can't be accounted because of this implementation detail.

This patchset removes this limitation by moving the PageKmemcg flag into
one of the free bits of the page->mem_cgroup pointer.  Also it formalizes
accesses to the page->mem_cgroup and page->obj_cgroups using new helpers,
adds several checks and removes a couple of obsolete functions.  As the
result the code became more robust with fewer open-coded bit tricks.

This patch (of 4):

Currently there are many open-coded reads of the page->mem_cgroup pointer,
as well as a couple of read helpers, which are barely used.

It creates an obstacle on a way to reuse some bits of the pointer for
storing additional bits of information.  In fact, we already do this for
slab pages, where the last bit indicates that a pointer has an attached
vector of objcg pointers instead of a regular memcg pointer.

This commits uses 2 existing helpers and introduces a new helper to
converts all read sides to calls of these helpers:
  struct mem_cgroup *page_memcg(struct page *page);
  struct mem_cgroup *page_memcg_rcu(struct page *page);
  struct mem_cgroup *page_memcg_check(struct page *page);

page_memcg_check() is intended to be used in cases when the page can be a
slab page and have a memcg pointer pointing at objcg vector.  It does
check the lowest bit, and if set, returns NULL.  page_memcg() contains a
VM_BUG_ON_PAGE() check for the page not being a slab page.

To make sure nobody uses a direct access, struct page's
mem_cgroup/obj_cgroups is converted to unsigned long memcg_data.
Signed-off-by: NRoman Gushchin <guro@fb.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAlexei Starovoitov <ast@kernel.org>
Reviewed-by: NShakeel Butt <shakeelb@google.com>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NMichal Hocko <mhocko@suse.com>
Link: https://lkml.kernel.org/r/20201027001657.3398190-1-guro@fb.com
Link: https://lkml.kernel.org/r/20201027001657.3398190-2-guro@fb.com
Link: https://lore.kernel.org/bpf/20201201215900.3569844-2-guro@fb.com
      bcfe06bf
  25. 14 10月, 2020 2 次提交
  27. 08 8月, 2020 7 次提交
  29. 18 6月, 2020 1 次提交
  31. 10 6月, 2020 1 次提交
  33. 03 6月, 2020 1 次提交
    • V
      mm, dump_page(): do not crash with invalid mapping pointer · 002ae705
      由 Vlastimil Babka 提交于 
      We have seen a following problem on a RPi4 with 1G RAM:

    BUG: Bad page state in process systemd-hwdb  pfn:35601
    page:ffff7e0000d58040 refcount:15 mapcount:131221 mapping:efd8fe765bc80080 index:0x1 compound_mapcount: -32767
    Unable to handle kernel paging request at virtual address efd8fe765bc80080
    Mem abort info:
      ESR = 0x96000004
      Exception class = DABT (current EL), IL = 32 bits
      SET = 0, FnV = 0
      EA = 0, S1PTW = 0
    Data abort info:
      ISV = 0, ISS = 0x00000004
      CM = 0, WnR = 0
    [efd8fe765bc80080] address between user and kernel address ranges
    Internal error: Oops: 96000004 [#1] SMP
    Modules linked in: btrfs libcrc32c xor xor_neon zlib_deflate raid6_pq mmc_block xhci_pci xhci_hcd usbcore sdhci_iproc sdhci_pltfm sdhci mmc_core clk_raspberrypi gpio_raspberrypi_exp pcie_brcmstb bcm2835_dma gpio_regulator phy_generic fixed sg scsi_mod efivarfs
    Supported: No, Unreleased kernel
    CPU: 3 PID: 408 Comm: systemd-hwdb Not tainted 5.3.18-8-default #1 SLE15-SP2 (unreleased)
    Hardware name: raspberrypi rpi/rpi, BIOS 2020.01 02/21/2020
    pstate: 40000085 (nZcv daIf -PAN -UAO)
    pc : __dump_page+0x268/0x368
    lr : __dump_page+0xc4/0x368
    sp : ffff000012563860
    x29: ffff000012563860 x28: ffff80003ddc4300
    x27: 0000000000000010 x26: 000000000000003f
    x25: ffff7e0000d58040 x24: 000000000000000f
    x23: efd8fe765bc80080 x22: 0000000000020095
    x21: efd8fe765bc80080 x20: ffff000010ede8b0
    x19: ffff7e0000d58040 x18: ffffffffffffffff
    x17: 0000000000000001 x16: 0000000000000007
    x15: ffff000011689708 x14: 3030386362353637
    x13: 6566386466653a67 x12: 6e697070616d2031
    x11: 32323133313a746e x10: 756f6370616d2035
    x9 : ffff00001168a840 x8 : ffff00001077a670
    x7 : 000000000000013d x6 : ffff0000118a43b5
    x5 : 0000000000000001 x4 : ffff80003dd9e2c8
    x3 : ffff80003dd9e2c8 x2 : 911c8d7c2f483500
    x1 : dead000000000100 x0 : efd8fe765bc80080
    Call trace:
     __dump_page+0x268/0x368
     bad_page+0xd4/0x168
     check_new_page_bad+0x80/0xb8
     rmqueue_bulk.constprop.26+0x4d8/0x788
     get_page_from_freelist+0x4d4/0x1228
     __alloc_pages_nodemask+0x134/0xe48
     alloc_pages_vma+0x198/0x1c0
     do_anonymous_page+0x1a4/0x4d8
     __handle_mm_fault+0x4e8/0x560
     handle_mm_fault+0x104/0x1e0
     do_page_fault+0x1e8/0x4c0
     do_translation_fault+0xb0/0xc0
     do_mem_abort+0x50/0xb0
     el0_da+0x24/0x28
    Code: f9401025 8b8018a0 9a851005 17ffffca (f94002a0)

Besides the underlying issue with page->mapping containing a bogus value
for some reason, we can see that __dump_page() crashed by trying to read
the pointer at mapping->host, turning a recoverable warning into full
Oops.

It can be expected that when page is reported as bad state for some
reason, the pointers there should not be trusted blindly.

So this patch treats all data in __dump_page() that depends on
page->mapping as lava, using probe_kernel_read_strict().  Ideally this
would include the dentry->d_parent recursively, but that would mean
changing printk handler for %pd.  Chances of reaching the dentry
printing part with an initially bogus mapping pointer should be rather
low, though.

Also prefix printing mapping->a_ops with a description of what is being
printed.  In case the value is bogus, %ps will print raw value instead
of the symbol name and then it's not obvious at all that it's printing
a_ops.
Reported-by: NPetr Tesarik <ptesarik@suse.cz>
Signed-off-by: NVlastimil Babka <vbabka@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Acked-by: NKirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Link: http://lkml.kernel.org/r/20200331165454.12263-1-vbabka@suse.czSigned-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      002ae705
  35. 03 4月, 2020 2 次提交
  37. 01 2月, 2020 2 次提交
    • Q
      mm/hotplug: silence a lockdep splat with printk() · 4a55c047
      由 Qian Cai 提交于 
      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.pwSigned-off-by: NQian Cai <cai@lca.pw>
Reviewed-by: NDavid Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Petr Mladek <pmladek@suse.com>
Cc: Steven Rostedt (VMware) <rostedt@goodmis.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      4a55c047
    • V
      mm/debug.c: always print flags in dump_page() · 5b57b8f2
      由 Vlastimil Babka 提交于 
      Commit 76a1850e ("mm/debug.c: __dump_page() prints an extra line")
inadvertently removed printing of page flags for pages that are neither
anon nor ksm nor have a mapping.  Fix that.

Using pr_cont() again would be a solution, but the commit explicitly
removed its use.  Avoiding the danger of mixing up split lines from
multiple CPUs might be beneficial for near-panic dumps like this, so fix
this without reintroducing pr_cont().

Link: http://lkml.kernel.org/r/9f884d5c-ca60-dc7b-219c-c081c755fab6@suse.cz
Fixes: 76a1850e ("mm/debug.c: __dump_page() prints an extra line")
Signed-off-by: NVlastimil Babka <vbabka@suse.cz>
Reported-by: NAnshuman Khandual <anshuman.khandual@arm.com>
Reported-by: NMichal Hocko <mhocko@kernel.org>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Qian Cai <cai@lca.pw>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Mike Rapoport <rppt@linux.ibm.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Pavel Tatashin <pavel.tatashin@microsoft.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      5b57b8f2
  39. 14 1月, 2020 1 次提交
  41. 16 11月, 2019 2 次提交
  43. 15 5月, 2019 1 次提交
  45. 30 3月, 2019 2 次提交
  47. 22 2月, 2019 1 次提交
    • R
      mm/debug.c: fix __dump_page() for poisoned pages · 311ade0e
      由 Robin Murphy 提交于 
      Evaluating page_mapping() on a poisoned page ends up dereferencing junk
and making PF_POISONED_CHECK() considerably crashier than intended:

    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
    user pgtable: 4k pages, 39-bit VAs, pgdp = 00000000c2f6ac38
    [0000000000000006] pgd=0000000000000000, pud=0000000000000000
    Internal error: Oops: 96000005 [#1] PREEMPT SMP
    Modules linked in:
    CPU: 2 PID: 491 Comm: bash Not tainted 5.0.0-rc1+ #1
    Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Dec 17 2018
    pstate: 00000005 (nzcv daif -PAN -UAO)
    pc : page_mapping+0x18/0x118
    lr : __dump_page+0x1c/0x398
    Process bash (pid: 491, stack limit = 0x000000004ebd4ecd)
    Call trace:
     page_mapping+0x18/0x118
     __dump_page+0x1c/0x398
     dump_page+0xc/0x18
     remove_store+0xbc/0x120
     dev_attr_store+0x18/0x28
     sysfs_kf_write+0x40/0x50
     kernfs_fop_write+0x130/0x1d8
     __vfs_write+0x30/0x180
     vfs_write+0xb4/0x1a0
     ksys_write+0x60/0xd0
     __arm64_sys_write+0x18/0x20
     el0_svc_common+0x94/0xf8
     el0_svc_handler+0x68/0x70
     el0_svc+0x8/0xc
    Code: f9400401 d1000422 f240003f 9a801040 (f9400402)
    ---[ end trace cdb5eb5bf435cecb ]---

Fix that by not inspecting the mapping until we've determined that it's
likely to be valid.  Now the above condition still ends up stopping the
kernel, but in the correct manner:

    page:ffffffbf20000000 is uninitialized and poisoned
    raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff
    raw: ffffffffffffffff ffffffffffffffff ffffffffffffffff ffffffffffffffff
    page dumped because: VM_BUG_ON_PAGE(PagePoisoned(p))
    ------------[ cut here ]------------
    kernel BUG at ./include/linux/mm.h:1006!
    Internal error: Oops - BUG: 0 [#1] PREEMPT SMP
    Modules linked in:
    CPU: 1 PID: 483 Comm: bash Not tainted 5.0.0-rc1+ #3
    Hardware name: ARM LTD ARM Juno Development Platform/ARM Juno Development Platform, BIOS EDK II Dec 17 2018
    pstate: 40000005 (nZcv daif -PAN -UAO)
    pc : remove_store+0xbc/0x120
    lr : remove_store+0xbc/0x120
    ...

Link: http://lkml.kernel.org/r/03b53ee9d7e76cda4b9b5e1e31eea080db033396.1550071778.git.robin.murphy@arm.com
Fixes: 1c6fb1d8 ("mm: print more information about mapping in __dump_page")
Signed-off-by: NRobin Murphy <robin.murphy@arm.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
      311ade0e
  49. 08 2月, 2019 1 次提交