linux-stable.git/mm/memory.c, branch v5.2.9

mm, swap: fix race between swapoff and some swap operations

2019-07-31T05:24:55+00:00

[ Upstream commit eb085574a7526c4375965c5fbf7e5b0c19cdd336 ]

When swapin is performed, after getting the swap entry information from
the page table, system will swap in the swap entry, without any lock held
to prevent the swap device from being swapoff.  This may cause the race
like below,

CPU 1				CPU 2
-----				-----
				do_swap_page
				  swapin_readahead
				    __read_swap_cache_async
swapoff				      swapcache_prepare
  p->swap_map = NULL		        __swap_duplicate
					  p->swap_map[?] /* !!! NULL pointer access */

Because swapoff is usually done when system shutdown only, the race may
not hit many people in practice.  But it is still a race need to be fixed.

To fix the race, get_swap_device() is added to check whether the specified
swap entry is valid in its swap device.  If so, it will keep the swap
entry valid via preventing the swap device from being swapoff, until
put_swap_device() is called.

Because swapoff() is very rare code path, to make the normal path runs as
fast as possible, rcu_read_lock/unlock() and synchronize_rcu() instead of
reference count is used to implement get/put_swap_device().  >From
get_swap_device() to put_swap_device(), RCU reader side is locked, so
synchronize_rcu() in swapoff() will wait until put_swap_device() is
called.

In addition to swap_map, cluster_info, etc.  data structure in the struct
swap_info_struct, the swap cache radix tree will be freed after swapoff,
so this patch fixes the race between swap cache looking up and swapoff
too.

Races between some other swap cache usages and swapoff are fixed too via
calling synchronize_rcu() between clearing PageSwapCache() and freeing
swap cache data structure.

Another possible method to fix this is to use preempt_off() +
stop_machine() to prevent the swap device from being swapoff when its data
structure is being accessed.  The overhead in hot-path of both methods is
similar.  The advantages of RCU based method are,

1. stop_machine() may disturb the normal execution code path on other
   CPUs.

2. File cache uses RCU to protect its radix tree.  If the similar
   mechanism is used for swap cache too, it is easier to share code
   between them.

3. RCU is used to protect swap cache in total_swapcache_pages() and
   exit_swap_address_space() already.  The two mechanisms can be
   merged to simplify the logic.

Link: http://lkml.kernel.org/r/20190522015423.14418-1-ying.huang@intel.com
Fixes: 235b62176712 ("mm/swap: add cluster lock")
Signed-off-by: "Huang, Ying" 
Reviewed-by: Andrea Parri 
Not-nacked-by: Hugh Dickins 
Cc: Andrea Arcangeli 
Cc: Paul E. McKenney 
Cc: Daniel Jordan 
Cc: Michal Hocko 
Cc: Minchan Kim 
Cc: Johannes Weiner 
Cc: Tim Chen 
Cc: Mel Gorman 
Cc: Jérôme Glisse 
Cc: Yang Shi 
Cc: David Rientjes 
Cc: Rik van Riel 
Cc: Jan Kara 
Cc: Dave Jiang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

mm: use down_read_killable for locking mmap_sem in access_remote_vm

2019-07-31T05:24:55+00:00

[ Upstream commit 1e426fe28261b03f297992e89da3320b42816f4e ]

This function is used by ptrace and proc files like /proc/pid/cmdline and
/proc/pid/environ.

Access_remote_vm never returns error codes, all errors are ignored and
only size of successfully read data is returned.  So, if current task was
killed we'll simply return 0 (bytes read).

Mmap_sem could be locked for a long time or forever if something goes
wrong.  Using a killable lock permits cleanup of stuck tasks and
simplifies investigation.

Link: http://lkml.kernel.org/r/156007494202.3335.16782303099589302087.stgit@buzz
Signed-off-by: Konstantin Khlebnikov 
Reviewed-by: Michal Koutný 
Acked-by: Oleg Nesterov 
Acked-by: Michal Hocko 
Cc: Alexey Dobriyan 
Cc: Matthew Wilcox 
Cc: Cyrill Gorcunov 
Cc: Kirill Tkhai 
Cc: Al Viro 
Cc: Roman Gushchin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

treewide: Add SPDX license identifier for missed files

2019-05-21T08:50:45+00:00

Add SPDX license identifiers to all files which:

 - Have no license information of any form

 - Have EXPORT_.*_SYMBOL_GPL inside which was used in the
   initial scan/conversion to ignore the file

These files fall under the project license, GPL v2 only. The resulting SPDX
license identifier is:

  GPL-2.0-only

Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

mm: introduce new vm_map_pages() and vm_map_pages_zero() API

2019-05-14T16:47:50+00:00

Patch series "mm: Use vm_map_pages() and vm_map_pages_zero() API", v5.

This patch (of 5):

Previouly drivers have their own way of mapping range of kernel
pages/memory into user vma and this was done by invoking vm_insert_page()
within a loop.

As this pattern is common across different drivers, it can be generalized
by creating new functions and using them across the drivers.

vm_map_pages() is the API which can be used to map kernel memory/pages in
drivers which have considered vm_pgoff

vm_map_pages_zero() is the API which can be used to map a range of kernel
memory/pages in drivers which have not considered vm_pgoff.  vm_pgoff is
passed as default 0 for those drivers.

We _could_ then at a later "fix" these drivers which are using
vm_map_pages_zero() to behave according to the normal vm_pgoff offsetting
simply by removing the _zero suffix on the function name and if that
causes regressions, it gives us an easy way to revert.

Tested on Rockchip hardware and display is working, including talking to
Lima via prime.

Link: http://lkml.kernel.org/r/751cb8a0f4c3e67e95c58a3b072937617f338eea.1552921225.git.jrdr.linux@gmail.com
Signed-off-by: Souptick Joarder 
Suggested-by: Russell King 
Suggested-by: Matthew Wilcox 
Reviewed-by: Mike Rapoport 
Tested-by: Heiko Stuebner 
Cc: Michal Hocko 
Cc: "Kirill A. Shutemov" 
Cc: Vlastimil Babka 
Cc: Rik van Riel 
Cc: Stephen Rothwell 
Cc: Peter Zijlstra 
Cc: Robin Murphy 
Cc: Joonsoo Kim 
Cc: Thierry Reding 
Cc: Kees Cook 
Cc: Marek Szyprowski 
Cc: Stefan Richter 
Cc: Sandy Huang 
Cc: David Airlie 
Cc: Oleksandr Andrushchenko 
Cc: Joerg Roedel 
Cc: Pawel Osciak 
Cc: Kyungmin Park 
Cc: Boris Ostrovsky 
Cc: Juergen Gross 
Cc: Mauro Carvalho Chehab 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/mmu_notifier: use correct mmu_notifier events for each invalidation

2019-05-14T16:47:49+00:00

This updates each existing invalidation to use the correct mmu notifier
event that represent what is happening to the CPU page table.  See the
patch which introduced the events to see the rational behind this.

Link: http://lkml.kernel.org/r/20190326164747.24405-7-jglisse@redhat.com
Signed-off-by: Jérôme Glisse 
Reviewed-by: Ralph Campbell 
Reviewed-by: Ira Weiny 
Cc: Christian König 
Cc: Joonas Lahtinen 
Cc: Jani Nikula 
Cc: Rodrigo Vivi 
Cc: Jan Kara 
Cc: Andrea Arcangeli 
Cc: Peter Xu 
Cc: Felix Kuehling 
Cc: Jason Gunthorpe 
Cc: Ross Zwisler 
Cc: Dan Williams 
Cc: Paolo Bonzini 
Cc: Radim Krcmar 
Cc: Michal Hocko 
Cc: Christian Koenig 
Cc: John Hubbard 
Cc: Arnd Bergmann 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/mmu_notifier: contextual information for event triggering invalidation

2019-05-14T16:47:49+00:00

CPU page table update can happens for many reasons, not only as a result
of a syscall (munmap(), mprotect(), mremap(), madvise(), ...) but also as
a result of kernel activities (memory compression, reclaim, migration,
...).

Users of mmu notifier API track changes to the CPU page table and take
specific action for them.  While current API only provide range of virtual
address affected by the change, not why the changes is happening.

This patchset do the initial mechanical convertion of all the places that
calls mmu_notifier_range_init to also provide the default MMU_NOTIFY_UNMAP
event as well as the vma if it is know (most invalidation happens against
a given vma).  Passing down the vma allows the users of mmu notifier to
inspect the new vma page protection.

The MMU_NOTIFY_UNMAP is always the safe default as users of mmu notifier
should assume that every for the range is going away when that event
happens.  A latter patch do convert mm call path to use a more appropriate
events for each call.

This is done as 2 patches so that no call site is forgotten especialy
as it uses this following coccinelle patch:

%<----------------------------------------------------------------------
@@
identifier I1, I2, I3, I4;
@@
static inline void mmu_notifier_range_init(struct mmu_notifier_range *I1,
+enum mmu_notifier_event event,
+unsigned flags,
+struct vm_area_struct *vma,
struct mm_struct *I2, unsigned long I3, unsigned long I4) { ... }

@@
@@
-#define mmu_notifier_range_init(range, mm, start, end)
+#define mmu_notifier_range_init(range, event, flags, vma, mm, start, end)

@@
expression E1, E3, E4;
identifier I1;
@@
<...
mmu_notifier_range_init(E1,
+MMU_NOTIFY_UNMAP, 0, I1,
I1->vm_mm, E3, E4)
...>

@@
expression E1, E2, E3, E4;
identifier FN, VMA;
@@
FN(..., struct vm_area_struct *VMA, ...) {
<...
mmu_notifier_range_init(E1,
+MMU_NOTIFY_UNMAP, 0, VMA,
E2, E3, E4)
...> }

@@
expression E1, E2, E3, E4;
identifier FN, VMA;
@@
FN(...) {
struct vm_area_struct *VMA;
<...
mmu_notifier_range_init(E1,
+MMU_NOTIFY_UNMAP, 0, VMA,
E2, E3, E4)
...> }

@@
expression E1, E2, E3, E4;
identifier FN;
@@
FN(...) {
<...
mmu_notifier_range_init(E1,
+MMU_NOTIFY_UNMAP, 0, NULL,
E2, E3, E4)
...> }
---------------------------------------------------------------------->%

Applied with:
spatch --all-includes --sp-file mmu-notifier.spatch fs/proc/task_mmu.c --in-place
spatch --sp-file mmu-notifier.spatch --dir kernel/events/ --in-place
spatch --sp-file mmu-notifier.spatch --dir mm --in-place

Link: http://lkml.kernel.org/r/20190326164747.24405-6-jglisse@redhat.com
Signed-off-by: Jérôme Glisse 
Reviewed-by: Ralph Campbell 
Reviewed-by: Ira Weiny 
Cc: Christian König 
Cc: Joonas Lahtinen 
Cc: Jani Nikula 
Cc: Rodrigo Vivi 
Cc: Jan Kara 
Cc: Andrea Arcangeli 
Cc: Peter Xu 
Cc: Felix Kuehling 
Cc: Jason Gunthorpe 
Cc: Ross Zwisler 
Cc: Dan Williams 
Cc: Paolo Bonzini 
Cc: Radim Krcmar 
Cc: Michal Hocko 
Cc: Christian Koenig 
Cc: John Hubbard 
Cc: Arnd Bergmann 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'printk-for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk

2019-05-07T16:18:12+00:00

Pull printk updates from Petr Mladek:

 - Allow state reset of printk_once() calls.

 - Prevent crashes when dereferencing invalid pointers in vsprintf().
   Only the first byte is checked for simplicity.

 - Make vsprintf warnings consistent and inlined.

 - Treewide conversion of obsolete %pf, %pF to %ps, %pF printf
   modifiers.

 - Some clean up of vsprintf and test_printf code.

* tag 'printk-for-5.2' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk:
  lib/vsprintf: Make function pointer_string static
  vsprintf: Limit the length of inlined error messages
  vsprintf: Avoid confusion between invalid address and value
  vsprintf: Prevent crash when dereferencing invalid pointers
  vsprintf: Consolidate handling of unknown pointer specifiers
  vsprintf: Factor out %pO handler as kobject_string()
  vsprintf: Factor out %pV handler as va_format()
  vsprintf: Factor out %p[iI] handler as ip_addr_string()
  vsprintf: Do not check address of well-known strings
  vsprintf: Consistent %pK handling for kptr_restrict == 0
  vsprintf: Shuffle restricted_pointer()
  printk: Tie printk_once / printk_deferred_once into .data.once for reset
  treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively
  lib/test_printf: Switch to bitmap_zalloc()

treewide: Switch printk users from %pf and %pF to %ps and %pS, respectively

2019-04-09T12:19:06+00:00

%pF and %pf are functionally equivalent to %pS and %ps conversion
specifiers. The former are deprecated, therefore switch the current users
to use the preferred variant.

The changes have been produced by the following command:

	git grep -l '%p[fF]' | grep -v '^\(tools\|Documentation\)/' | \
	while read i; do perl -i -pe 's/%pf/%ps/g; s/%pF/%pS/g;' $i; done

And verifying the result.

Link: http://lkml.kernel.org/r/20190325193229.23390-1-sakari.ailus@linux.intel.com
Cc: Andy Shevchenko 
Cc: linux-arm-kernel@lists.infradead.org
Cc: sparclinux@vger.kernel.org
Cc: linux-um@lists.infradead.org
Cc: xen-devel@lists.xenproject.org
Cc: linux-acpi@vger.kernel.org
Cc: linux-pm@vger.kernel.org
Cc: drbd-dev@lists.linbit.com
Cc: linux-block@vger.kernel.org
Cc: linux-mmc@vger.kernel.org
Cc: linux-nvdimm@lists.01.org
Cc: linux-pci@vger.kernel.org
Cc: linux-scsi@vger.kernel.org
Cc: linux-btrfs@vger.kernel.org
Cc: linux-f2fs-devel@lists.sourceforge.net
Cc: linux-mm@kvack.org
Cc: ceph-devel@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Sakari Ailus 
Acked-by: David Sterba  (for btrfs)
Acked-by: Mike Rapoport  (for mm/memblock.c)
Acked-by: Bjorn Helgaas  (for drivers/pci)
Acked-by: Rafael J. Wysocki 
Signed-off-by: Petr Mladek

asm-generic/tlb: Remove tlb_flush_mmu_free()

2019-04-03T08:33:01+00:00

As the comment notes; it is a potentially dangerous operation. Just
use tlb_flush_mmu(), that will skip the (double) TLB invalidate if
it really isn't needed anyway.

No change in behavior intended.

Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Will Deacon 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Dave Hansen 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Peter Zijlstra 
Cc: Rik van Riel 
Cc: Thomas Gleixner 
Signed-off-by: Ingo Molnar

asm-generic/tlb, arch: Provide CONFIG_HAVE_MMU_GATHER_PAGE_SIZE

2019-04-03T08:32:40+00:00

Move the mmu_gather::page_size things into the generic code instead of
PowerPC specific bits.

No change in behavior intended.

Signed-off-by: Peter Zijlstra (Intel) 
Acked-by: Will Deacon 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Aneesh Kumar K.V 
Cc: Borislav Petkov 
Cc: Dave Hansen 
Cc: H. Peter Anvin 
Cc: Linus Torvalds 
Cc: Nick Piggin 
Cc: Peter Zijlstra 
Cc: Rik van Riel 
Cc: Thomas Gleixner 
Signed-off-by: Ingo Molnar