mmotm 2019-07-24-21-39 uploaded

mmotm 2019-07-24-21-39 uploaded

[akpm]

The mm-of-the-moment snapshot 2019-07-24-21-39 has been uploaded to

   http://www.ozlabs.org/~akpm/mmotm/

mmotm-readme.txt says

README for mm-of-the-moment:

http://www.ozlabs.org/~akpm/mmotm/

This is a snapshot of my -mm patch queue.  Uploaded at random hopefully
more than once a week.

You will need quilt to apply these patches to the latest Linus release (5.x
or 5.x-rcY).  The series file is in broken-out.tar.gz and is duplicated in
http://ozlabs.org/~akpm/mmotm/series

The file broken-out.tar.gz contains two datestamp files: .DATE and
.DATE-yyyy-mm-dd-hh-mm-ss.  Both contain the string yyyy-mm-dd-hh-mm-ss,
followed by the base kernel version against which this patch series is to
be applied.

This tree is partially included in linux-next.  To see which patches are
included in linux-next, consult the `series' file.  Only the patches
within the #NEXT_PATCHES_START/#NEXT_PATCHES_END markers are included in
linux-next.


A full copy of the full kernel tree with the linux-next and mmotm patches
already applied is available through git within an hour of the mmotm
release.  Individual mmotm releases are tagged.  The master branch always
points to the latest release, so it's constantly rebasing.

http://git.cmpxchg.org/cgit.cgi/linux-mmotm.git/



The directory http://www.ozlabs.org/~akpm/mmots/ (mm-of-the-second)
contains daily snapshots of the -mm tree.  It is updated more frequently
than mmotm, and is untested.

A git copy of this tree is available at

	http://git.cmpxchg.org/cgit.cgi/linux-mmots.git/

and use of this tree is similar to
http://git.cmpxchg.org/cgit.cgi/linux-mmotm.git/, described above.


This mmotm tree contains the following patches against 5.3-rc1:
(patches marked "*" will be included in linux-next)

  origin.patch
* docs-signal-fix-a-kernel-doc-markup.patch
* revert-kmemleak-allow-to-coexist-with-fault-injection.patch
* ocfs2-remove-set-but-not-used-variable-last_hash.patch
* mm-vmscan-check-if-mem-cgroup-is-disabled-or-not-before-calling-memcg-slab-shrinker.patch
* mm-migrate-fix-reference-check-race-between-__find_get_block-and-migration.patch
* mm-compaction-avoid-100%-cpu-usage-during-compaction-when-a-task-is-killed.patch
* kasan-remove-clang-version-check-for-kasan_stack.patch
* proc-kpageflags-prevent-an-integer-overflow-in-stable_page_flags.patch
* proc-kpageflags-do-not-use-uninitialized-struct-pages.patch
* mm-document-zone-device-struct-page-field-usage.patch
* mm-hmm-fix-zone_device-anon-page-mapping-reuse.patch
* mm-hmm-fix-bad-subpage-pointer-in-try_to_unmap_one.patch
* mm-hmm-fix-bad-subpage-pointer-in-try_to_unmap_one-v3.patch
* ubsan-build-ubsanc-more-conservatively.patch
* page-flags-prioritize-kasan-bits-over-last-cpuid.patch
* coredump-split-pipe-command-whitespace-before-expanding-template.patch
* mm-migrate-initialize-pud_entry-in-migrate_vma.patch
* mm-hotplug-remove-unneeded-return-for-void-function.patch
* cgroup-kselftest-relax-fs_spec-checks.patch
* asm-generic-fix-wtype-limits-compiler-warnings.patch
* asm-generic-fix-wtype-limits-compiler-warnings-fix.patch
* asm-generic-fix-wtype-limits-compiler-warnings-v2.patch
* acpi-scan-acquire-device_hotplug_lock-in-acpi_scan_init.patch
* mm-mempolicy-make-the-behavior-consistent-when-mpol_mf_move-and-mpol_mf_strict-were-specified.patch
* mm-mempolicy-make-the-behavior-consistent-when-mpol_mf_move-and-mpol_mf_strict-were-specified-v4.patch
* mm-mempolicy-handle-vma-with-unmovable-pages-mapped-correctly-in-mbind.patch
* mm-mempolicy-handle-vma-with-unmovable-pages-mapped-correctly-in-mbind-v4.patch
* kbuild-clean-compressed-initramfs-image.patch
* ocfs2-use-jbd2_inode-dirty-range-scoping.patch
* jbd2-remove-jbd2_journal_inode_add_.patch
* ocfs2-clear-zero-in-unaligned-direct-io.patch
* ocfs2-clear-zero-in-unaligned-direct-io-checkpatch-fixes.patch
* ocfs2-wait-for-recovering-done-after-direct-unlock-request.patch
* ocfs2-checkpoint-appending-truncate-log-transaction-before-flushing.patch
* ramfs-support-o_tmpfile.patch
  mm.patch
* mm-slab-extend-slab-shrink-to-shrink-all-memcg-caches.patch
* mm-slab-move-memcg_cache_params-structure-to-mm-slabh.patch
* memremap-move-from-kernel-to-mm.patch
* mm-page_poison-fix-a-typo-in-a-comment.patch
* mm-rmapc-remove-set-but-not-used-variable-cstart.patch
* mm-introduce-page_size.patch
* mm-introduce-page_shift.patch
* mm-introduce-page_shift-fix.patch
* mm-introduce-compound_nr.patch
* mm-replace-list_move_tail-with-add_page_to_lru_list_tail.patch
* mm-filemap-rewrite-mapping_needs_writeback-in-less-fancy-manner.patch
* mm-throttle-allocators-when-failing-reclaim-over-memoryhigh.patch
* mm-throttle-allocators-when-failing-reclaim-over-memoryhigh-fix.patch
* mm-vmscan-expose-cgroup_ino-for-memcg-reclaim-tracepoints.patch
* mm-gup-add-make_dirty-arg-to-put_user_pages_dirty_lock.patch
* drivers-gpu-drm-via-convert-put_page-to-put_user_page.patch
* net-xdp-convert-put_page-to-put_user_page.patch
* mm-remove-redundant-assignment-of-entry.patch
* mm-mmap-fix-the-adjusted-length-error.patch
* mm-memory_hotplug-remove-move_pfn_range.patch
* mm-memory_hotplug-remove-move_pfn_range-fix.patch
* drivers-base-nodec-simplify-unregister_memory_block_under_nodes.patch
* mm-sparse-fix-memory-leak-of-sparsemap_buf-in-aliged-memory.patch
* mm-sparse-fix-memory-leak-of-sparsemap_buf-in-aliged-memory-fix.patch
* mm-sparse-fix-align-without-power-of-2-in-sparse_buffer_alloc.patch
* mm-vmalloc-do-not-keep-unpurged-areas-in-the-busy-tree.patch
* mm-vmalloc-modify-struct-vmap_area-to-reduce-its-size.patch
* mm-compaction-clear-total_migratefree_scanned-before-scanning-a-new-zone.patch
* mm-compaction-clear-total_migratefree_scanned-before-scanning-a-new-zone-fix.patch
* mm-compaction-clear-total_migratefree_scanned-before-scanning-a-new-zone-fix-fix.patch
* mm-compaction-clear-total_migratefree_scanned-before-scanning-a-new-zone-fix-2.patch
* mm-compaction-clear-total_migratefree_scanned-before-scanning-a-new-zone-fix-2-fix.patch
* mm-oom-avoid-printk-iteration-under-rcu.patch
* mm-oom-avoid-printk-iteration-under-rcu-fix.patch
* mm-oom_killer-add-task-uid-to-info-message-on-an-oom-kill.patch
* mm-oom_killer-add-task-uid-to-info-message-on-an-oom-kill-fix.patch
* psi-annotate-refault-stalls-from-io-submission.patch
* psi-annotate-refault-stalls-from-io-submission-fix.patch
* psi-annotate-refault-stalls-from-io-submission-fix-2.patch
* mm-introduce-madv_cold.patch
* mm-change-pageref_reclaim_clean-with-page_refreclaim.patch
* mm-account-nr_isolated_xxx-in-_lru_page.patch
* mm-introduce-madv_pageout.patch
* mm-factor-out-common-parts-between-madv_cold-and-madv_pageout.patch
* zpool-add-malloc_support_movable-to-zpool_driver.patch
* zswap-use-movable-memory-if-zpool-support-allocate-movable-memory.patch
* mm-proportional-memorylowmin-reclaim.patch
* mm-make-memoryemin-the-baseline-for-utilisation-determination.patch
* mm-make-memoryemin-the-baseline-for-utilisation-determination-fix.patch
* mm-vmscan-remove-unused-lru_pages-argument.patch
* mm-dont-expose-page-to-fast-gup-before-its-ready.patch
* info-task-hung-in-generic_file_write_iter.patch
* info-task-hung-in-generic_file_write-fix.patch
* kernel-hung_taskc-monitor-killed-tasks.patch
* hung_task-allow-printing-warnings-every-check-interval.patch
* lib-genallocc-export-symbol-addr_in_gen_pool.patch
* lib-genallocc-rename-addr_in_gen_pool-to-gen_pool_has_addr.patch
* lib-genallocc-rename-addr_in_gen_pool-to-gen_pool_has_addr-fix.patch
* string-add-stracpy-and-stracpy_pad-mechanisms.patch
* kernel-doc-core-api-include-stringh-into-core-api.patch
* kernel-doc-core-api-include-stringh-into-core-api-v2.patch
* lib-fix-possible-incorrect-result-from-rational-fractions-helper.patch
* checkpatch-dont-interpret-stack-dumps-as-commit-ids.patch
* checkpatch-improve-spdx-license-checking.patch
* checkpatchpl-warn-on-invalid-commit-id.patch
* checkpatch-add-_notifier_head-as-var-definition.patch
* fat-add-nobarrier-to-workaround-the-strange-behavior-of-device.patch
* cpumask-nicer-for_each_cpumask_and-signature.patch
* kexec-bail-out-upon-sigkill-when-allocating-memory.patch
* aio-simplify-read_events.patch
* kgdb-dont-use-a-notifier-to-enter-kgdb-at-panic-call-directly.patch
* ipc-consolidate-all-xxxctl_down-functions.patch
  linux-next.patch
  diff-sucks.patch
* pinctrl-fix-pxa2xxc-build-warnings.patch
* mm-treewide-clarify-pgtable_page_ctordtor-naming.patch
* drivers-tty-serial-sh-scic-suppress-warning.patch
* fix-read-buffer-overflow-in-delta-ipc.patch
  make-sure-nobodys-leaking-resources.patch
  releasing-resources-with-children.patch
  mutex-subsystem-synchro-test-module.patch
  kernel-forkc-export-kernel_thread-to-modules.patch
  workaround-for-a-pci-restoring-bug.patch

Re: mmotm 2019-07-24-21-39 uploaded (mm/memcontrol)

[Randy Dunlap]

On 7/24/19 9:40 PM, akpm@linux-foundation.org wrote:
> The mm-of-the-moment snapshot 2019-07-24-21-39 has been uploaded to
> 
>    http://www.ozlabs.org/~akpm/mmotm/
> 
> mmotm-readme.txt says
> 
> README for mm-of-the-moment:
> 
> http://www.ozlabs.org/~akpm/mmotm/
> 
> This is a snapshot of my -mm patch queue.  Uploaded at random hopefully
> more than once a week.
> 
> You will need quilt to apply these patches to the latest Linus release (5.x
> or 5.x-rcY).  The series file is in broken-out.tar.gz and is duplicated in
> http://ozlabs.org/~akpm/mmotm/series
> 

on i386:

ld: mm/memcontrol.o: in function `mem_cgroup_handle_over_high':
memcontrol.c:(.text+0x6235): undefined reference to `__udivdi3'


-- 
~Randy

Re: mmotm 2019-07-24-21-39 uploaded (mm/memcontrol)

[Andrew Morton]

On Thu, 25 Jul 2019 15:02:59 -0700 Randy Dunlap <rdunlap@infradead.org> wrote:

> On 7/24/19 9:40 PM, akpm@linux-foundation.org wrote:
> > The mm-of-the-moment snapshot 2019-07-24-21-39 has been uploaded to
> > 
> >    http://www.ozlabs.org/~akpm/mmotm/
> > 
> > mmotm-readme.txt says
> > 
> > README for mm-of-the-moment:
> > 
> > http://www.ozlabs.org/~akpm/mmotm/
> > 
> > This is a snapshot of my -mm patch queue.  Uploaded at random hopefully
> > more than once a week.
> > 
> > You will need quilt to apply these patches to the latest Linus release (5.x
> > or 5.x-rcY).  The series file is in broken-out.tar.gz and is duplicated in
> > http://ozlabs.org/~akpm/mmotm/series
> > 
> 
> on i386:
> 
> ld: mm/memcontrol.o: in function `mem_cgroup_handle_over_high':
> memcontrol.c:(.text+0x6235): undefined reference to `__udivdi3'

Thanks.  This?

--- a/mm/memcontrol.c~mm-throttle-allocators-when-failing-reclaim-over-memoryhigh-fix-fix
+++ a/mm/memcontrol.c
@@ -2414,8 +2414,9 @@ void mem_cgroup_handle_over_high(void)
 	 */
 	clamped_high = max(high, 1UL);
 
-	overage = ((u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT)
-		/ clamped_high;
+	overage = (u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT;
+	do_div(overage, clamped_high);
+
 	penalty_jiffies = ((u64)overage * overage * HZ)
 		>> (MEMCG_DELAY_PRECISION_SHIFT + MEMCG_DELAY_SCALING_SHIFT);
 
_

Re: mmotm 2019-07-24-21-39 uploaded (mm/memcontrol)

[Randy Dunlap]

On 7/25/19 4:39 PM, Andrew Morton wrote:
> On Thu, 25 Jul 2019 15:02:59 -0700 Randy Dunlap <rdunlap@infradead.org> wrote:
> 
>> On 7/24/19 9:40 PM, akpm@linux-foundation.org wrote:
>>> The mm-of-the-moment snapshot 2019-07-24-21-39 has been uploaded to
>>>
>>>    http://www.ozlabs.org/~akpm/mmotm/
>>>
>>> mmotm-readme.txt says
>>>
>>> README for mm-of-the-moment:
>>>
>>> http://www.ozlabs.org/~akpm/mmotm/
>>>
>>> This is a snapshot of my -mm patch queue.  Uploaded at random hopefully
>>> more than once a week.
>>>
>>> You will need quilt to apply these patches to the latest Linus release (5.x
>>> or 5.x-rcY).  The series file is in broken-out.tar.gz and is duplicated in
>>> http://ozlabs.org/~akpm/mmotm/series
>>>
>>
>> on i386:
>>
>> ld: mm/memcontrol.o: in function `mem_cgroup_handle_over_high':
>> memcontrol.c:(.text+0x6235): undefined reference to `__udivdi3'
> 
> Thanks.  This?


Yes, that works.  Thanks.

Acked-by: Randy Dunlap <rdunlap@infradead.org>


> --- a/mm/memcontrol.c~mm-throttle-allocators-when-failing-reclaim-over-memoryhigh-fix-fix
> +++ a/mm/memcontrol.c
> @@ -2414,8 +2414,9 @@ void mem_cgroup_handle_over_high(void)
>  	 */
>  	clamped_high = max(high, 1UL);
>  
> -	overage = ((u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT)
> -		/ clamped_high;
> +	overage = (u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT;
> +	do_div(overage, clamped_high);
> +
>  	penalty_jiffies = ((u64)overage * overage * HZ)
>  		>> (MEMCG_DELAY_PRECISION_SHIFT + MEMCG_DELAY_SCALING_SHIFT);
>  
> _
> 


-- 
~Randy

Re: mmotm 2019-07-24-21-39 uploaded (mm/memcontrol)

[Nathan Chancellor]

On Thu, Jul 25, 2019 at 04:39:59PM -0700, Andrew Morton wrote:
> On Thu, 25 Jul 2019 15:02:59 -0700 Randy Dunlap <rdunlap@infradead.org> wrote:
> 
> > On 7/24/19 9:40 PM, akpm@linux-foundation.org wrote:
> > > The mm-of-the-moment snapshot 2019-07-24-21-39 has been uploaded to
> > > 
> > >    http://www.ozlabs.org/~akpm/mmotm/
> > > 
> > > mmotm-readme.txt says
> > > 
> > > README for mm-of-the-moment:
> > > 
> > > http://www.ozlabs.org/~akpm/mmotm/
> > > 
> > > This is a snapshot of my -mm patch queue.  Uploaded at random hopefully
> > > more than once a week.
> > > 
> > > You will need quilt to apply these patches to the latest Linus release (5.x
> > > or 5.x-rcY).  The series file is in broken-out.tar.gz and is duplicated in
> > > http://ozlabs.org/~akpm/mmotm/series
> > > 
> > 
> > on i386:
> > 
> > ld: mm/memcontrol.o: in function `mem_cgroup_handle_over_high':
> > memcontrol.c:(.text+0x6235): undefined reference to `__udivdi3'
> 
> Thanks.  This?
> 
> --- a/mm/memcontrol.c~mm-throttle-allocators-when-failing-reclaim-over-memoryhigh-fix-fix
> +++ a/mm/memcontrol.c
> @@ -2414,8 +2414,9 @@ void mem_cgroup_handle_over_high(void)
>  	 */
>  	clamped_high = max(high, 1UL);
>  
> -	overage = ((u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT)
> -		/ clamped_high;
> +	overage = (u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT;
> +	do_div(overage, clamped_high);
> +
>  	penalty_jiffies = ((u64)overage * overage * HZ)
>  		>> (MEMCG_DELAY_PRECISION_SHIFT + MEMCG_DELAY_SCALING_SHIFT);
>  
> _
> 

This causes a build error on arm:


In file included from ../arch/arm/include/asm/div64.h:127,
                 from ../include/linux/kernel.h:18,
                 from ../include/linux/page_counter.h:6,
                 from ../mm/memcontrol.c:25:
../mm/memcontrol.c: In function 'mem_cgroup_handle_over_high':
../include/asm-generic/div64.h:222:28: warning: comparison of distinct pointer types lacks a cast
  222 |  (void)(((typeof((n)) *)0) == ((uint64_t *)0)); \
      |                            ^~
../mm/memcontrol.c:2423:2: note: in expansion of macro 'do_div'
 2423 |  do_div(overage, clamped_high);
      |  ^~~~~~
In file included from ../arch/arm/include/asm/atomic.h:11,
                 from ../include/linux/atomic.h:7,
                 from ../include/linux/page_counter.h:5,
                 from ../mm/memcontrol.c:25:
../include/asm-generic/div64.h:235:25: warning: right shift count >= width of type [-Wshift-count-overflow]
  235 |  } else if (likely(((n) >> 32) == 0)) {  \
      |                         ^~
../include/linux/compiler.h:77:40: note: in definition of macro 'likely'
   77 | # define likely(x) __builtin_expect(!!(x), 1)
      |                                        ^
../mm/memcontrol.c:2423:2: note: in expansion of macro 'do_div'
 2423 |  do_div(overage, clamped_high);
      |  ^~~~~~
In file included from ../arch/arm/include/asm/div64.h:127,
                 from ../include/linux/kernel.h:18,
                 from ../include/linux/page_counter.h:6,
                 from ../mm/memcontrol.c:25:
../include/asm-generic/div64.h:239:22: error: passing argument 1 of '__div64_32' from incompatible pointer type [-Werror=incompatible-pointer-types]
  239 |   __rem = __div64_32(&(n), __base); \
      |                      ^~~~
      |                      |
      |                      long unsigned int *
../mm/memcontrol.c:2423:2: note: in expansion of macro 'do_div'
 2423 |  do_div(overage, clamped_high);
      |  ^~~~~~
In file included from ../include/linux/kernel.h:18,
                 from ../include/linux/page_counter.h:6,
                 from ../mm/memcontrol.c:25:
../arch/arm/include/asm/div64.h:33:45: note: expected 'uint64_t *' {aka 'long long unsigned int *'} but argument is of type 'long unsigned int *'
   33 | static inline uint32_t __div64_32(uint64_t *n, uint32_t base)
      |                                   ~~~~~~~~~~^
cc1: some warnings being treated as errors
make[3]: *** [../scripts/Makefile.build:274: mm/memcontrol.o] Error 1
make[2]: *** [../Makefile:1768: mm/memcontrol.o] Error 2
make[1]: *** [/home/nathan/cbl/linux-next/Makefile:330: __build_one_by_one] Error 2
make: *** [Makefile:179: sub-make] Error 2


I fixed it up like so but no idea if that is the ideal function to use.


diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 5c7b9facb0eb..04b621f1cb6b 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2419,8 +2419,8 @@ void mem_cgroup_handle_over_high(void)
 	 */
 	clamped_high = max(high, 1UL);
 
-	overage = (u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT;
-	do_div(overage, clamped_high);
+	overage = div64_u64((u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT,
+			    clamped_high);
 
 	penalty_jiffies = ((u64)overage * overage * HZ)
 		>> (MEMCG_DELAY_PRECISION_SHIFT + MEMCG_DELAY_SCALING_SHIFT);

Re: mmotm 2019-07-24-21-39 uploaded (mm/memcontrol)

[Andrew Morton]

On Fri, 26 Jul 2019 20:42:05 -0700 Nathan Chancellor <natechancellor@gmail.com> wrote:

> > @@ -2414,8 +2414,9 @@ void mem_cgroup_handle_over_high(void)
> >  	 */
> >  	clamped_high = max(high, 1UL);
> >  
> > -	overage = ((u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT)
> > -		/ clamped_high;
> > +	overage = (u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT;
> > +	do_div(overage, clamped_high);
> > +
> >  	penalty_jiffies = ((u64)overage * overage * HZ)
> >  		>> (MEMCG_DELAY_PRECISION_SHIFT + MEMCG_DELAY_SCALING_SHIFT);
> >  
> > _
> > 
> 
> This causes a build error on arm:
> 

Ah.

It's rather unclear why that u64 cast is there anyway.  We're dealing
with ulongs all over this code.  The below will suffice.

Chris, please take a look?

--- a/mm/memcontrol.c~mm-throttle-allocators-when-failing-reclaim-over-memoryhigh-fix-fix-fix
+++ a/mm/memcontrol.c
@@ -2415,7 +2415,7 @@ void mem_cgroup_handle_over_high(void)
 	clamped_high = max(high, 1UL);
 
 	overage = (u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT;
-	do_div(overage, clamped_high);
+	overage /= clamped_high;
 
 	penalty_jiffies = ((u64)overage * overage * HZ)
 		>> (MEMCG_DELAY_PRECISION_SHIFT + MEMCG_DELAY_SCALING_SHIFT);
_

Re: mmotm 2019-07-24-21-39 uploaded (mm/memcontrol)

[Nathan Chancellor]

On Fri, Jul 26, 2019 at 09:19:52PM -0700, Andrew Morton wrote:
> On Fri, 26 Jul 2019 20:42:05 -0700 Nathan Chancellor <natechancellor@gmail.com> wrote:
> 
> > > @@ -2414,8 +2414,9 @@ void mem_cgroup_handle_over_high(void)
> > >  	 */
> > >  	clamped_high = max(high, 1UL);
> > >  
> > > -	overage = ((u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT)
> > > -		/ clamped_high;
> > > +	overage = (u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT;
> > > +	do_div(overage, clamped_high);
> > > +
> > >  	penalty_jiffies = ((u64)overage * overage * HZ)
> > >  		>> (MEMCG_DELAY_PRECISION_SHIFT + MEMCG_DELAY_SCALING_SHIFT);
> > >  
> > > _
> > > 
> > 
> > This causes a build error on arm:
> > 
> 
> Ah.
> 
> It's rather unclear why that u64 cast is there anyway.  We're dealing
> with ulongs all over this code.  The below will suffice.

I was thinking the same thing.

> Chris, please take a look?
> 
> --- a/mm/memcontrol.c~mm-throttle-allocators-when-failing-reclaim-over-memoryhigh-fix-fix-fix
> +++ a/mm/memcontrol.c
> @@ -2415,7 +2415,7 @@ void mem_cgroup_handle_over_high(void)
>  	clamped_high = max(high, 1UL);
>  
>  	overage = (u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT;
> -	do_div(overage, clamped_high);
> +	overage /= clamped_high;
>  
>  	penalty_jiffies = ((u64)overage * overage * HZ)
>  		>> (MEMCG_DELAY_PRECISION_SHIFT + MEMCG_DELAY_SCALING_SHIFT);
> _
> 

I assume this will get folded in with the original patch but for
completeness (multi_v7_defconfig + CONFIG_MEMCG):

Tested-by: Nathan Chancellor <natechancellor@gmail.com>

Thanks for the quick fix!

Re: mmotm 2019-07-24-21-39 uploaded (mm/memcontrol)

[Chris Down]

u64 division: truly the gift that keeps on giving. Thanks Andrew for following 
up on these.

Andrew Morton writes:
>Ah.
>
>It's rather unclear why that u64 cast is there anyway.  We're dealing
>with ulongs all over this code.  The below will suffice.

This place in particular uses u64 to make sure we don't overflow when left 
shifting, since the numbers can get pretty big (and that's somewhat needed due 
to the need for high precision when calculating the penalty jiffies). It's ok 
if the output after division is an unsigned long, just the intermediate steps 
need to have enough precision.

>Chris, please take a look?
>
>--- a/mm/memcontrol.c~mm-throttle-allocators-when-failing-reclaim-over-memoryhigh-fix-fix-fix
>+++ a/mm/memcontrol.c
>@@ -2415,7 +2415,7 @@ void mem_cgroup_handle_over_high(void)
> 	clamped_high = max(high, 1UL);
>
> 	overage = (u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT;
>-	do_div(overage, clamped_high);
>+	overage /= clamped_high;

I think this isn't going to work because left shifting by 
MEMCG_DELAY_PRECISION_SHIFT can make the number bigger than ULONG_MAX, which 
may cause wraparound -- we need to retain the u64 until we divide.

Maybe div_u64 will satisfy both ARM and i386? ie.

diff --git mm/memcontrol.c mm/memcontrol.c
index 5c7b9facb0eb..e12a47e96154 100644
--- mm/memcontrol.c
+++ mm/memcontrol.c
@@ -2419,8 +2419,8 @@ void mem_cgroup_handle_over_high(void)
         */
        clamped_high = max(high, 1UL);
 
-       overage = (u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT;
-       do_div(overage, clamped_high);
+       overage = div_u64((u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT,
+                         clamped_high);
 
        penalty_jiffies = ((u64)overage * overage * HZ)
                >> (MEMCG_DELAY_PRECISION_SHIFT + MEMCG_DELAY_SCALING_SHIFT);

Re: mmotm 2019-07-24-21-39 uploaded (mm/memcontrol)

[Stephen Rothwell]

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Hi all,

On Sat, 27 Jul 2019 11:16:08 +0100 Chris Down <chris@chrisdown.name> wrote:
>
> u64 division: truly the gift that keeps on giving. Thanks Andrew for following 
> up on these.
> 
> Andrew Morton writes:
> >Ah.
> >
> >It's rather unclear why that u64 cast is there anyway.  We're dealing
> >with ulongs all over this code.  The below will suffice.  
> 
> This place in particular uses u64 to make sure we don't overflow when left 
> shifting, since the numbers can get pretty big (and that's somewhat needed due 
> to the need for high precision when calculating the penalty jiffies). It's ok 
> if the output after division is an unsigned long, just the intermediate steps 
> need to have enough precision.
> 
> >Chris, please take a look?
> >
> >--- a/mm/memcontrol.c~mm-throttle-allocators-when-failing-reclaim-over-memoryhigh-fix-fix-fix
> >+++ a/mm/memcontrol.c
> >@@ -2415,7 +2415,7 @@ void mem_cgroup_handle_over_high(void)
> > 	clamped_high = max(high, 1UL);
> >
> > 	overage = (u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT;
> >-	do_div(overage, clamped_high);
> >+	overage /= clamped_high;  
> 
> I think this isn't going to work because left shifting by 
> MEMCG_DELAY_PRECISION_SHIFT can make the number bigger than ULONG_MAX, which 
> may cause wraparound -- we need to retain the u64 until we divide.
> 
> Maybe div_u64 will satisfy both ARM and i386? ie.
> 
> diff --git mm/memcontrol.c mm/memcontrol.c
> index 5c7b9facb0eb..e12a47e96154 100644
> --- mm/memcontrol.c
> +++ mm/memcontrol.c
> @@ -2419,8 +2419,8 @@ void mem_cgroup_handle_over_high(void)
>          */
>         clamped_high = max(high, 1UL);
>  
> -       overage = (u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT;
> -       do_div(overage, clamped_high);
> +       overage = div_u64((u64)(usage - high) << MEMCG_DELAY_PRECISION_SHIFT,
> +                         clamped_high);
>  
>         penalty_jiffies = ((u64)overage * overage * HZ)
>                 >> (MEMCG_DELAY_PRECISION_SHIFT + MEMCG_DELAY_SCALING_SHIFT);  

I have applied this to the akpm-current tree in linux-next today.

-- 
Cheers,
Stephen Rothwell

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