linux-toradex.git/fs/proc, branch v5.17-rc7

proc: fix documentation and description of pagemap

2022-03-05T19:08:33+00:00

Since bit 57 was exported for uffd-wp write-protected (commit
fb8e37f35a2f: "mm/pagemap: export uffd-wp protection information"),
fixing it can reduce some unnecessary confusion.

Link: https://lkml.kernel.org/r/20220301044538.3042713-1-yun.zhou@windriver.com
Fixes: fb8e37f35a2fe1 ("mm/pagemap: export uffd-wp protection information")
Signed-off-by: Yun Zhou 
Reviewed-by: Peter Xu 
Cc: Jonathan Corbet 
Cc: Tiberiu A Georgescu 
Cc: Florian Schmidt 
Cc: Ivan Teterevkov 
Cc: SeongJae Park 
Cc: Yang Shi 
Cc: David Hildenbrand 
Cc: Axel Rasmussen 
Cc: Miaohe Lin 
Cc: Andrea Arcangeli 
Cc: Colin Cross 
Cc: Alistair Popple 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: refactor vm_area_struct::anon_vma_name usage code

2022-03-05T19:08:32+00:00

Avoid mixing strings and their anon_vma_name referenced pointers by
using struct anon_vma_name whenever possible.  This simplifies the code
and allows easier sharing of anon_vma_name structures when they
represent the same name.

[surenb@google.com: fix comment]

Link: https://lkml.kernel.org/r/20220223153613.835563-1-surenb@google.com
Link: https://lkml.kernel.org/r/20220224231834.1481408-1-surenb@google.com
Signed-off-by: Suren Baghdasaryan 
Suggested-by: Matthew Wilcox 
Suggested-by: Michal Hocko 
Acked-by: Michal Hocko 
Cc: Colin Cross 
Cc: Sumit Semwal 
Cc: Dave Hansen 
Cc: Kees Cook 
Cc: "Kirill A. Shutemov" 
Cc: Vlastimil Babka 
Cc: Johannes Weiner 
Cc: "Eric W. Biederman" 
Cc: Christian Brauner 
Cc: Alexey Gladkov 
Cc: Sasha Levin 
Cc: Chris Hyser 
Cc: Davidlohr Bueso 
Cc: Peter Collingbourne 
Cc: Xiaofeng Cao 
Cc: David Hildenbrand 
Cc: Cyrill Gorcunov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs/proc: task_mmu.c: don't read mapcount for migration entry

2022-02-12T01:55:00+00:00

The syzbot reported the below BUG:

  kernel BUG at include/linux/page-flags.h:785!
  invalid opcode: 0000 [#1] PREEMPT SMP KASAN
  CPU: 1 PID: 4392 Comm: syz-executor560 Not tainted 5.16.0-rc6-syzkaller #0
  Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
  RIP: 0010:PageDoubleMap include/linux/page-flags.h:785 [inline]
  RIP: 0010:__page_mapcount+0x2d2/0x350 mm/util.c:744
  Call Trace:
    page_mapcount include/linux/mm.h:837 [inline]
    smaps_account+0x470/0xb10 fs/proc/task_mmu.c:466
    smaps_pte_entry fs/proc/task_mmu.c:538 [inline]
    smaps_pte_range+0x611/0x1250 fs/proc/task_mmu.c:601
    walk_pmd_range mm/pagewalk.c:128 [inline]
    walk_pud_range mm/pagewalk.c:205 [inline]
    walk_p4d_range mm/pagewalk.c:240 [inline]
    walk_pgd_range mm/pagewalk.c:277 [inline]
    __walk_page_range+0xe23/0x1ea0 mm/pagewalk.c:379
    walk_page_vma+0x277/0x350 mm/pagewalk.c:530
    smap_gather_stats.part.0+0x148/0x260 fs/proc/task_mmu.c:768
    smap_gather_stats fs/proc/task_mmu.c:741 [inline]
    show_smap+0xc6/0x440 fs/proc/task_mmu.c:822
    seq_read_iter+0xbb0/0x1240 fs/seq_file.c:272
    seq_read+0x3e0/0x5b0 fs/seq_file.c:162
    vfs_read+0x1b5/0x600 fs/read_write.c:479
    ksys_read+0x12d/0x250 fs/read_write.c:619
    do_syscall_x64 arch/x86/entry/common.c:50 [inline]
    do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
    entry_SYSCALL_64_after_hwframe+0x44/0xae

The reproducer was trying to read /proc/$PID/smaps when calling
MADV_FREE at the mean time.  MADV_FREE may split THPs if it is called
for partial THP.  It may trigger the below race:

           CPU A                         CPU B
           -----                         -----
  smaps walk:                      MADV_FREE:
  page_mapcount()
    PageCompound()
                                   split_huge_page()
    page = compound_head(page)
    PageDoubleMap(page)

When calling PageDoubleMap() this page is not a tail page of THP anymore
so the BUG is triggered.

This could be fixed by elevated refcount of the page before calling
mapcount, but that would prevent it from counting migration entries, and
it seems overkilling because the race just could happen when PMD is
split so all PTE entries of tail pages are actually migration entries,
and smaps_account() does treat migration entries as mapcount == 1 as
Kirill pointed out.

Add a new parameter for smaps_account() to tell this entry is migration
entry then skip calling page_mapcount().  Don't skip getting mapcount
for device private entries since they do track references with mapcount.

Pagemap also has the similar issue although it was not reported.  Fixed
it as well.

[shy828301@gmail.com: v4]
  Link: https://lkml.kernel.org/r/20220203182641.824731-1-shy828301@gmail.com
[nathan@kernel.org: avoid unused variable warning in pagemap_pmd_range()]
  Link: https://lkml.kernel.org/r/20220207171049.1102239-1-nathan@kernel.org
Link: https://lkml.kernel.org/r/20220120202805.3369-1-shy828301@gmail.com
Fixes: e9b61f19858a ("thp: reintroduce split_huge_page()")
Signed-off-by: Yang Shi 
Signed-off-by: Nathan Chancellor 
Reported-by: syzbot+1f52b3a18d5633fa7f82@syzkaller.appspotmail.com
Acked-by: David Hildenbrand 
Cc: "Kirill A. Shutemov" 
Cc: Jann Horn 
Cc: Matthew Wilcox 
Cc: Alexey Dobriyan 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

proc: remove PDE_DATA() completely

2022-01-22T06:33:37+00:00

Remove PDE_DATA() completely and replace it with pde_data().

[akpm@linux-foundation.org: fix naming clash in drivers/nubus/proc.c]
[akpm@linux-foundation.org: now fix it properly]

Link: https://lkml.kernel.org/r/20211124081956.87711-2-songmuchun@bytedance.com
Signed-off-by: Muchun Song 
Acked-by: Christian Brauner 
Cc: Alexey Dobriyan 
Cc: Alexey Gladkov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

fs: proc: store PDE()->data into inode->i_private

2022-01-22T06:33:37+00:00

PDE_DATA(inode) is introduced to get user private data and hide the
layout of struct proc_dir_entry.  The inode->i_private is used to do the
same thing as well.  Save a copy of user private data to inode->
i_private when proc inode is allocated.  This means the user also can
get their private data by inode->i_private.

Introduce pde_data() to wrap inode->i_private so that we can remove
PDE_DATA() from fs/proc/generic.c and make PTE_DATE() as a wrapper of
pde_data().  It will be easier if we decide to remove PDE_DATE() in the
future.

Link: https://lkml.kernel.org/r/20211124081956.87711-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song 
Acked-by: Christian Brauner 
Cc: Alexey Dobriyan 
Cc: Alexey Gladkov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kernel/sysctl.c: rename sysctl_init() to sysctl_init_bases()

2022-01-22T06:33:36+00:00

Rename sysctl_init() to sysctl_init_bases() so to reflect exactly what
this is doing.

Link: https://lkml.kernel.org/r/20211129211943.640266-4-mcgrof@kernel.org
Signed-off-by: Luis Chamberlain 
Cc: Al Viro 
Cc: Anil S Keshavamurthy 
Cc: Antti Palosaari 
Cc: Christian Brauner 
Cc: "David S. Miller" 
Cc: Eric Biederman 
Cc: Eric Biggers 
Cc: Iurii Zaikin 
Cc: Kees Cook 
Cc: Lukas Middendorf 
Cc: Masami Hiramatsu 
Cc: "Naveen N. Rao" 
Cc: Stephen Kitt 
Cc: Xiaoming Ni 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sysctl: add and use base directory declarer and registration helper

2022-01-22T06:33:36+00:00

Patch series "sysctl: add and use base directory declarer and
registration helper".

In this patch series we start addressing base directories, and so we
start with the "fs" sysctls.  The end goal is we end up completely
moving all "fs" sysctl knobs out from kernel/sysctl.

This patch (of 6):

Add a set of helpers which can be used to declare and register base
directory sysctls on their own.  We do this so we can later move each of
the base sysctl directories like "fs", "kernel", etc, to their own
respective files instead of shoving the declarations and registrations
all on kernel/sysctl.c.  The lazy approach has caught up and with this,
we just end up extending the list of base directories / sysctls on one
file and this makes maintenance difficult due to merge conflicts from
many developers.

The declarations are used first by kernel/sysctl.c for registration its
own base which over time we'll try to clean up.  It will be used in the
next patch to demonstrate how to cleanly deal with base sysctl
directories.

[mcgrof@kernel.org: null-terminate the ctl_table arrays]
  Link: https://lkml.kernel.org/r/YafJY3rXDYnjK/gs@bombadil.infradead.org

Link: https://lkml.kernel.org/r/20211129211943.640266-1-mcgrof@kernel.org
Link: https://lkml.kernel.org/r/20211129211943.640266-2-mcgrof@kernel.org
Signed-off-by: Luis Chamberlain 
Cc: Al Viro 
Cc: Kees Cook 
Cc: Iurii Zaikin 
Cc: Xiaoming Ni 
Cc: Eric Biederman 
Cc: Stephen Kitt 
Cc: Lukas Middendorf 
Cc: Antti Palosaari 
Cc: Christian Brauner 
Cc: Eric Biggers 
Cc: "Naveen N. Rao" 
Cc: "David S. Miller" 
Cc: Masami Hiramatsu 
Cc: Anil S Keshavamurthy 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sysctl: move maxolduid as a sysctl specific const

2022-01-22T06:33:36+00:00

The maxolduid value is only shared for sysctl purposes for use on a max
range.  Just stuff this into our shared const array.

[akpm@linux-foundation.org: fix sysctl_vals[], per Mickaël]

Link: https://lkml.kernel.org/r/20211129205548.605569-5-mcgrof@kernel.org
Signed-off-by: Luis Chamberlain 
Signed-off-by: Mickaël Salaün 
Cc: Al Viro 
Cc: Andy Shevchenko 
Cc: Antti Palosaari 
Cc: Eric Biederman 
Cc: Iurii Zaikin 
Cc: "J. Bruce Fields" 
Cc: Jeff Layton 
Cc: Kees Cook 
Cc: Lukas Middendorf 
Cc: Stephen Kitt 
Cc: Xiaoming Ni 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sysctl: share unsigned long const values

2022-01-22T06:33:35+00:00

Provide a way to share unsigned long values.  This will allow others to
not have to re-invent these values.

Link: https://lkml.kernel.org/r/20211124231435.1445213-9-mcgrof@kernel.org
Signed-off-by: Luis Chamberlain 
Cc: Al Viro 
Cc: Amir Goldstein 
Cc: Andy Shevchenko 
Cc: Antti Palosaari 
Cc: Arnd Bergmann 
Cc: Benjamin Herrenschmidt 
Cc: Benjamin LaHaise 
Cc: Clemens Ladisch 
Cc: David Airlie 
Cc: Douglas Gilbert 
Cc: Eric Biederman 
Cc: Greg Kroah-Hartman 
Cc: Iurii Zaikin 
Cc: James E.J. Bottomley 
Cc: Jani Nikula 
Cc: Jani Nikula 
Cc: Jan Kara 
Cc: Joel Becker 
Cc: John Ogness 
Cc: Joonas Lahtinen 
Cc: Joseph Qi 
Cc: Julia Lawall 
Cc: Kees Cook 
Cc: Lukas Middendorf 
Cc: Mark Fasheh 
Cc: Martin K. Petersen 
Cc: Paul Turner 
Cc: Peter Zijlstra 
Cc: Petr Mladek 
Cc: Phillip Potter 
Cc: Qing Wang 
Cc: "Rafael J. Wysocki" 
Cc: Rodrigo Vivi 
Cc: Sebastian Reichel 
Cc: Sergey Senozhatsky 
Cc: Stephen Kitt 
Cc: Steven Rostedt (VMware) 
Cc: Suren Baghdasaryan 
Cc: Tetsuo Handa 
Cc: "Theodore Ts'o" 
Cc: Xiaoming Ni 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sysctl: add helper to register a sysctl mount point

2022-01-22T06:33:35+00:00

The way to create a subdirectory on top of sysctl_mount_point is a bit
obscure, and *why* we do that even so more.  Provide a helper which
makes it clear why we do this.

[akpm@linux-foundation.org: export register_sysctl_mount_point() to
modules]

Link: https://lkml.kernel.org/r/20211124231435.1445213-4-mcgrof@kernel.org
Signed-off-by: Luis Chamberlain 
Suggested-by: "Eric W. Biederman" 
Cc: Al Viro 
Cc: Amir Goldstein 
Cc: Andy Shevchenko 
Cc: Antti Palosaari 
Cc: Arnd Bergmann 
Cc: Benjamin Herrenschmidt 
Cc: Benjamin LaHaise 
Cc: Clemens Ladisch 
Cc: David Airlie 
Cc: Douglas Gilbert 
Cc: Greg Kroah-Hartman 
Cc: Iurii Zaikin 
Cc: James E.J. Bottomley 
Cc: Jani Nikula 
Cc: Jani Nikula 
Cc: Jan Kara 
Cc: Joel Becker 
Cc: John Ogness 
Cc: Joonas Lahtinen 
Cc: Joseph Qi 
Cc: Julia Lawall 
Cc: Kees Cook 
Cc: Lukas Middendorf 
Cc: Mark Fasheh 
Cc: Martin K. Petersen 
Cc: Paul Turner 
Cc: Peter Zijlstra 
Cc: Petr Mladek 
Cc: Phillip Potter 
Cc: Qing Wang 
Cc: "Rafael J. Wysocki" 
Cc: Rodrigo Vivi 
Cc: Sebastian Reichel 
Cc: Sergey Senozhatsky 
Cc: Stephen Kitt 
Cc: Steven Rostedt (VMware) 
Cc: Suren Baghdasaryan 
Cc: Tetsuo Handa 
Cc: "Theodore Ts'o" 
Cc: Xiaoming Ni 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds