15 Jun, 2018
1 commit
-
mm/*.c files use symbolic and octal styles for permissions.
Using octal and not symbolic permissions is preferred by many as more
readable.https://lkml.org/lkml/2016/8/2/1945
Prefer the direct use of octal for permissions.
Done using
$ scripts/checkpatch.pl -f --types=SYMBOLIC_PERMS --fix-inplace mm/*.c
and some typing.Before: $ git grep -P -w "0[0-7]{3,3}" mm | wc -l
44
After: $ git grep -P -w "0[0-7]{3,3}" mm | wc -l
86Miscellanea:
o Whitespace neatening around these conversions.
Link: http://lkml.kernel.org/r/2e032ef111eebcd4c5952bae86763b541d373469.1522102887.git.joe@perches.com
Signed-off-by: Joe Perches
Acked-by: David Rientjes
Acked-by: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
06 Apr, 2018
1 commit
-
The early_param() is only called during kernel initialization, So Linux
marks the functions of it with __init macro to save memory.But it forgot to mark the early_page_owner_param(). So, Make it __init
as well.Link: http://lkml.kernel.org/r/20180117034736.26963-1-douly.fnst@cn.fujitsu.com
Signed-off-by: Dou Liyang
Reviewed-by: Andrew Morton
Cc: Vlastimil Babka
Cc: Michal Hocko
Cc: Greg Kroah-Hartman
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
29 Mar, 2018
1 commit
-
This patch fixes commit 5f48f0bd4e36 ("mm, page_owner: skip unnecessary
stack_trace entries").Because if we skip first two entries then logic of checking count value
as 2 for recursion is broken and code will go in one depth recursion.so we need to check only one call of _RET_IP(__set_page_owner) while
checking for recursion.Current Backtrace while checking for recursion:-
(save_stack) from (__set_page_owner) // (But recursion returns true here)
(__set_page_owner) from (get_page_from_freelist)
(get_page_from_freelist) from (__alloc_pages_nodemask)
(__alloc_pages_nodemask) from (depot_save_stack)
(depot_save_stack) from (save_stack) // recursion should return true here
(save_stack) from (__set_page_owner)
(__set_page_owner) from (get_page_from_freelist)
(get_page_from_freelist) from (__alloc_pages_nodemask+)
(__alloc_pages_nodemask) from (depot_save_stack)
(depot_save_stack) from (save_stack)
(save_stack) from (__set_page_owner)
(__set_page_owner) from (get_page_from_freelist)Correct Backtrace with fix:
(save_stack) from (__set_page_owner) // recursion returned true here
(__set_page_owner) from (get_page_from_freelist)
(get_page_from_freelist) from (__alloc_pages_nodemask+)
(__alloc_pages_nodemask) from (depot_save_stack)
(depot_save_stack) from (save_stack)
(save_stack) from (__set_page_owner)
(__set_page_owner) from (get_page_from_freelist)Link: http://lkml.kernel.org/r/1521607043-34670-1-git-send-email-maninder1.s@samsung.com
Fixes: 5f48f0bd4e36 ("mm, page_owner: skip unnecessary stack_trace entries")
Signed-off-by: Maninder Singh
Signed-off-by: Vaneet Narang
Acked-by: Vlastimil Babka
Cc: Michal Hocko
Cc: Oscar Salvador
Cc: Greg Kroah-Hartman
Cc: Ayush Mittal
Cc: Prakash Gupta
Cc: Vinayak Menon
Cc: Vasyl Gomonovych
Cc: Amit Sahrawat
Cc:
Cc: Vaneet Narang
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
01 Feb, 2018
2 commits
-
Remove two redundant assignments in init_pages_in_zone().
[osalvador@techadventures.net: v3]
Link: http://lkml.kernel.org/r/20180117124513.GA876@techadventures.net
[akpm@linux-foundation.org: coding style tweaks]
Link: http://lkml.kernel.org/r/20180110084355.GA22822@techadventures.net
Signed-off-by: Oscar Salvador
Acked-by: Michal Hocko
Acked-by: Vlastimil Babka
Cc: Joonsoo Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Fix ptr_ret.cocci warnings:
mm/page_owner.c:639:1-3: WARNING: PTR_ERR_OR_ZERO can be used
Use PTR_ERR_OR_ZERO rather than if(IS_ERR(...)) + PTR_ERR
Generated by: scripts/coccinelle/api/ptr_ret.cocci
Link: http://lkml.kernel.org/r/1511824101-9597-1-git-send-email-gomonovych@gmail.com
Signed-off-by: Vasyl Gomonovych
Acked-by: Vlastimil Babka
Acked-by: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
20 Jan, 2018
1 commit
-
When setting page_owner = on, the following warning can be seen in the
boot log:WARNING: CPU: 0 PID: 0 at mm/page_alloc.c:2537 drain_all_pages+0x171/0x1a0
Modules linked in:
CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0-rc7-next-20180109-1-default+ #7
Hardware name: Dell Inc. Latitude E7470/0T6HHJ, BIOS 1.11.3 11/09/2016
RIP: 0010:drain_all_pages+0x171/0x1a0
Call Trace:
init_page_owner+0x4e/0x260
start_kernel+0x3e6/0x4a6
? set_init_arg+0x55/0x55
secondary_startup_64+0xa5/0xb0
Code: c5 ed ff 89 df 48 c7 c6 20 3b 71 82 e8 f9 4b 52 00 3b 05 d7 0b f8 00 89 c3 72 d5 5b 5d 41 5This warning is shown because we are calling drain_all_pages() in
init_early_allocated_pages(), but mm_percpu_wq is not up yet, it is being
set up later on in kernel_init_freeable() -> init_mm_internals().Link: http://lkml.kernel.org/r/20180109153921.GA13070@techadventures.net
Signed-off-by: Oscar Salvador
Acked-by: Joonsoo Kim
Cc: Vlastimil Babka
Cc: Michal Hocko
Cc: Ayush Mittal
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
16 Nov, 2017
1 commit
-
Maximum page order can be at max 10 which can be accomodated in short
data type(2 bytes). last_migrate_reason is defined as enum type whose
values can be accomodated in short data type (2 bytes).Total structure size is currently 16 bytes but after changing structure
size it goes to 12 bytes.Vlastimil said:
"Looks like it works, so why not.
Before:
[ 0.001000] allocated 50331648 bytes of page_ext
After:
[ 0.001000] allocated 41943040 bytes of page_ext"Link: http://lkml.kernel.org/r/1507623917-37991-1-git-send-email-ayush.m@samsung.com
Signed-off-by: Ayush Mittal
Acked-by: Vlastimil Babka
Cc: Vinayak Menon
Cc: Amit Sahrawat
Cc: Vaneet Narang
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
02 Nov, 2017
1 commit
-
Many source files in the tree are missing licensing information, which
makes it harder for compliance tools to determine the correct license.By default all files without license information are under the default
license of the kernel, which is GPL version 2.Update the files which contain no license information with the 'GPL-2.0'
SPDX license identifier. The SPDX identifier is a legally binding
shorthand, which can be used instead of the full boiler plate text.This patch is based on work done by Thomas Gleixner and Kate Stewart and
Philippe Ombredanne.How this work was done:
Patches were generated and checked against linux-4.14-rc6 for a subset of
the use cases:
- file had no licensing information it it.
- file was a */uapi/* one with no licensing information in it,
- file was a */uapi/* one with existing licensing information,Further patches will be generated in subsequent months to fix up cases
where non-standard license headers were used, and references to license
had to be inferred by heuristics based on keywords.The analysis to determine which SPDX License Identifier to be applied to
a file was done in a spreadsheet of side by side results from of the
output of two independent scanners (ScanCode & Windriver) producing SPDX
tag:value files created by Philippe Ombredanne. Philippe prepared the
base worksheet, and did an initial spot review of a few 1000 files.The 4.13 kernel was the starting point of the analysis with 60,537 files
assessed. Kate Stewart did a file by file comparison of the scanner
results in the spreadsheet to determine which SPDX license identifier(s)
to be applied to the file. She confirmed any determination that was not
immediately clear with lawyers working with the Linux Foundation.Criteria used to select files for SPDX license identifier tagging was:
- Files considered eligible had to be source code files.
- Make and config files were included as candidates if they contained >5
lines of source
- File already had some variant of a license header in it (even if
Reviewed-by: Philippe Ombredanne
Reviewed-by: Thomas Gleixner
Signed-off-by: Greg Kroah-Hartman
14 Sep, 2017
1 commit
-
The page_owner stacktrace always begin as follows:
[] save_stack+0x40/0xc8
[] __set_page_owner+0x3c/0x6cThese two entries do not provide any useful information and limits the
available stacktrace depth. The page_owner stacktrace was skipping
caller function from stack entries but this was missed with commit
f2ca0b557107 ("mm/page_owner: use stackdepot to store stacktrace")Example page_owner entry after the patch:
Page allocated via order 0, mask 0x8(ffffff80085fb714)
PFN 654411 type Movable Block 639 type CMA Flags 0x0(ffffffbe5c7f12c0)
[] post_alloc_hook+0x70/0x80
...
[] msm_comm_try_state+0x5f8/0x14f4
[] msm_vidc_open+0x5e4/0x7d0
[] msm_v4l2_open+0xa8/0x224Link: http://lkml.kernel.org/r/1504078343-28754-2-git-send-email-guptap@codeaurora.org
Fixes: f2ca0b557107 ("mm/page_owner: use stackdepot to store stacktrace")
Signed-off-by: Prakash Gupta
Acked-by: Vlastimil Babka
Cc: Catalin Marinas
Cc: Joonsoo Kim
Cc: Michal Hocko
Cc: Russell King
Cc: Will Deacon
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
07 Sep, 2017
2 commits
-
init_pages_in_zone() is run under zone->lock, which means a long lock
time and disabled interrupts on large machines. This is currently not
an issue since it runs early in boot, but a later patch will change
that.However, like other pfn scanners, we don't actually need zone->lock even
when other cpus are running. The only potentially dangerous operation
here is reading bogus buddy page owner due to race, and we already know
how to handle that. The worst that can happen is that we skip some
early allocated pages, which should not affect the debugging power of
page_owner noticeably.Link: http://lkml.kernel.org/r/20170720134029.25268-4-vbabka@suse.cz
Signed-off-by: Vlastimil Babka
Acked-by: Michal Hocko
Cc: Joonsoo Kim
Cc: Mel Gorman
Cc: Yang Shi
Cc: Laura Abbott
Cc: Vinayak Menon
Cc: zhong jiang
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
In init_pages_in_zone() we currently use the generic set_page_owner()
function to initialize page_owner info for early allocated pages. This
means we needlessly do lookup_page_ext() twice for each page, and more
importantly save_stack(), which has to unwind the stack and find the
corresponding stack depot handle. Because the stack is always the same
for the initialization, unwind it once in init_pages_in_zone() and reuse
the handle. Also avoid the repeated lookup_page_ext().This can significantly reduce boot times with page_owner=on on large
machines, especially for kernels built without frame pointer, where the
stack unwinding is noticeably slower.[vbabka@suse.cz: don't duplicate code of __set_page_owner(), per Michal Hocko]
[akpm@linux-foundation.org: coding-style fixes]
[vbabka@suse.cz: create statically allocated fake stack trace for early allocated pages, per Michal]
Link: http://lkml.kernel.org/r/45813564-2342-fc8d-d31a-f4b68a724325@suse.cz
Link: http://lkml.kernel.org/r/20170720134029.25268-2-vbabka@suse.cz
Signed-off-by: Vlastimil Babka
Acked-by: Michal Hocko
Cc: Joonsoo Kim
Cc: Mel Gorman
Cc: Yang Shi
Cc: Laura Abbott
Cc: Vinayak Menon
Cc: zhong jiang
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
11 Jul, 2017
1 commit
-
pagetypeinfo_showmixedcount_print is found to take a lot of time to
complete and it does this holding the zone lock and disabling
interrupts. In some cases it is found to take more than a second (On a
2.4GHz,8Gb RAM,arm64 cpu).Avoid taking the zone lock similar to what is done by read_page_owner,
which means possibility of inaccurate results.Link: http://lkml.kernel.org/r/1498045643-12257-1-git-send-email-vinmenon@codeaurora.org
Signed-off-by: Vinayak Menon
Acked-by: Vlastimil Babka
Cc: Joonsoo Kim
Cc: zhongjiang
Cc: Sergey Senozhatsky
Cc: Sudip Mukherjee
Cc: Johannes Weiner
Cc: Mel Gorman
Cc: Michal Hocko
Cc: Sebastian Andrzej Siewior
Cc: David Rientjes
Cc: Minchan Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
08 Oct, 2016
2 commits
-
There is a memory waste problem if we define field on struct page_ext by
hard-coding. Entry size of struct page_ext includes the size of those
fields even if it is disabled at runtime. Now, extra memory request at
runtime is possible so page_owner don't need to define it's own fields
by hard-coding.This patch removes hard-coded define and uses extra memory for storing
page_owner information in page_owner. Most of code are just mechanical
changes.Link: http://lkml.kernel.org/r/1471315879-32294-7-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim
Acked-by: Vlastimil Babka
Cc: Minchan Kim
Cc: Michal Hocko
Cc: Sergey Senozhatsky
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
There is no reason that page_owner specific function resides on
vmstat.c.Link: http://lkml.kernel.org/r/1471315879-32294-4-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim
Reviewed-by: Sergey Senozhatsky
Acked-by: Vlastimil Babka
Cc: Minchan Kim
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
27 Jul, 2016
3 commits
-
Currently, we store each page's allocation stacktrace on corresponding
page_ext structure and it requires a lot of memory. This causes the
problem that memory tight system doesn't work well if page_owner is
enabled. Moreover, even with this large memory consumption, we cannot
get full stacktrace because we allocate memory at boot time and just
maintain 8 stacktrace slots to balance memory consumption. We could
increase it to more but it would make system unusable or change system
behaviour.To solve the problem, this patch uses stackdepot to store stacktrace.
It obviously provides memory saving but there is a drawback that
stackdepot could fail.stackdepot allocates memory at runtime so it could fail if system has
not enough memory. But, most of allocation stack are generated at very
early time and there are much memory at this time. So, failure would
not happen easily. And, one failure means that we miss just one page's
allocation stacktrace so it would not be a big problem. In this patch,
when memory allocation failure happens, we store special stracktrace
handle to the page that is failed to save stacktrace. With it, user can
guess memory usage properly even if failure happens.Memory saving looks as following. (4GB memory system with page_owner)
(before the patch -> after the patch)static allocation:
92274688 bytes -> 25165824 bytesdynamic allocation after boot + kernel build:
0 bytes -> 327680 bytestotal:
92274688 bytes -> 25493504 bytes72% reduction in total.
Note that implementation looks complex than someone would imagine
because there is recursion issue. stackdepot uses page allocator and
page_owner is called at page allocation. Using stackdepot in page_owner
could re-call page allcator and then page_owner. That is a recursion.
To detect and avoid it, whenever we obtain stacktrace, recursion is
checked and page_owner is set to dummy information if found. Dummy
information means that this page is allocated for page_owner feature
itself (such as stackdepot) and it's understandable behavior for user.[iamjoonsoo.kim@lge.com: mm-page_owner-use-stackdepot-to-store-stacktrace-v3]
Link: http://lkml.kernel.org/r/1464230275-25791-6-git-send-email-iamjoonsoo.kim@lge.com
Link: http://lkml.kernel.org/r/1466150259-27727-7-git-send-email-iamjoonsoo.kim@lge.com
Link: http://lkml.kernel.org/r/1464230275-25791-6-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim
Acked-by: Vlastimil Babka
Acked-by: Michal Hocko
Cc: Mel Gorman
Cc: Minchan Kim
Cc: Alexander Potapenko
Cc: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
split_page() calls set_page_owner() to set up page_owner to each pages.
But, it has a drawback that head page and the others have different
stacktrace because callsite of set_page_owner() is slightly differnt.
To avoid this problem, this patch copies head page's page_owner to the
others. It needs to introduce new function, split_page_owner() but it
also remove the other function, get_page_owner_gfp() so looks good to
do.Link: http://lkml.kernel.org/r/1464230275-25791-4-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim
Acked-by: Vlastimil Babka
Cc: Mel Gorman
Cc: Minchan Kim
Cc: Alexander Potapenko
Cc: Hugh Dickins
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
Currently, copy_page_owner() doesn't copy all the owner information. It
skips last_migrate_reason because copy_page_owner() is used for
migration and it will be properly set soon. But, following patch will
use copy_page_owner() and this skip will cause the problem that
allocated page has uninitialied last_migrate_reason. To prevent it,
this patch also copy last_migrate_reason in copy_page_owner().Link: http://lkml.kernel.org/r/1464230275-25791-3-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Joonsoo Kim
Acked-by: Vlastimil Babka
Cc: Mel Gorman
Cc: Minchan Kim
Cc: Alexander Potapenko
Cc: Hugh Dickins
Cc: Michal Hocko
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
25 Jun, 2016
1 commit
-
We have dereferenced page_ext before checking it. Lets check it first
and then used it.Fixes: f86e4271978b ("mm: check the return value of lookup_page_ext for all call sites")
Link: http://lkml.kernel.org/r/1465249059-7883-1-git-send-email-sudipm.mukherjee@gmail.com
Signed-off-by: Sudip Mukherjee
Acked-by: Vlastimil Babka
Cc: Joonsoo Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
04 Jun, 2016
1 commit
-
Per the discussion with Joonsoo Kim [1], we need check the return value
of lookup_page_ext() for all call sites since it might return NULL in
some cases, although it is unlikely, i.e. memory hotplug.Tested with ltp with "page_owner=0".
[1] http://lkml.kernel.org/r/20160519002809.GA10245@js1304-P5Q-DELUXE
[akpm@linux-foundation.org: fix build-breaking typos]
[arnd@arndb.de: fix build problems from lookup_page_ext]
Link: http://lkml.kernel.org/r/6285269.2CksypHdYp@wuerfel
[akpm@linux-foundation.org: coding-style fixes]
Link: http://lkml.kernel.org/r/1464023768-31025-1-git-send-email-yang.shi@linaro.org
Signed-off-by: Yang Shi
Signed-off-by: Arnd Bergmann
Cc: Joonsoo Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
20 May, 2016
2 commits
-
The function call overhead of get_pfnblock_flags_mask() is measurable in
the page free paths. This patch uses an inlined version that is faster.Signed-off-by: Mel Gorman
Acked-by: Vlastimil Babka
Cc: Jesper Dangaard Brouer
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
There is a system thats node's pfns are overlapped as follows:
-----pfn-------->
N0 N1 N2 N0 N1 N2Therefore, we need to care this overlapping when iterating pfn range.
There are one place in page_owner.c that iterates pfn range and it
doesn't consider this overlapping. Add it.Without this patch, above system could over count early allocated page
number before page_owner is activated.Signed-off-by: Joonsoo Kim
Acked-by: Vlastimil Babka
Cc: Rik van Riel
Cc: Johannes Weiner
Cc: Mel Gorman
Cc: Laura Abbott
Cc: Minchan Kim
Cc: Marek Szyprowski
Cc: Michal Nazarewicz
Cc: "Aneesh Kumar K.V"
Cc: "Rafael J. Wysocki"
Cc: Benjamin Herrenschmidt
Cc: Paul Mackerras
Cc: Michael Ellerman
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
18 Mar, 2016
1 commit
-
Kernel style prefers a single string over split strings when the string is
'user-visible'.Miscellanea:
- Add a missing newline
- Realign argumentsSigned-off-by: Joe Perches
Acked-by: Tejun Heo [percpu]
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
16 Mar, 2016
5 commits
-
The page_owner mechanism is useful for dealing with memory leaks. By
reading /sys/kernel/debug/page_owner one can determine the stack traces
leading to allocations of all pages, and find e.g. a buggy driver.This information might be also potentially useful for debugging, such as
the VM_BUG_ON_PAGE() calls to dump_page(). So let's print the stored
info from dump_page().Example output:
page:ffffea000292f1c0 count:1 mapcount:0 mapping:ffff8800b2f6cc18 index:0x91d
flags: 0x1fffff8001002c(referenced|uptodate|lru|mappedtodisk)
page dumped because: VM_BUG_ON_PAGE(1)
page->mem_cgroup:ffff8801392c5000
page allocated via order 0, migratetype Movable, gfp_mask 0x24213ca(GFP_HIGHUSER_MOVABLE|__GFP_COLD|__GFP_NOWARN|__GFP_NORETRY)
[] __alloc_pages_nodemask+0x134/0x230
[] alloc_pages_current+0x88/0x120
[] __page_cache_alloc+0xe6/0x120
[] __do_page_cache_readahead+0xdc/0x240
[] ondemand_readahead+0x135/0x260
[] page_cache_async_readahead+0x6c/0x70
[] generic_file_read_iter+0x3f2/0x760
[] __vfs_read+0xa7/0xd0
page has been migrated, last migrate reason: compactionSigned-off-by: Vlastimil Babka
Acked-by: Michal Hocko
Cc: Joonsoo Kim
Cc: Minchan Kim
Cc: Sasha Levin
Cc: "Kirill A. Shutemov"
Cc: Mel Gorman
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
During migration, page_owner info is now copied with the rest of the
page, so the stacktrace leading to free page allocation during migration
is overwritten. For debugging purposes, it might be however useful to
know that the page has been migrated since its initial allocation. This
might happen many times during the lifetime for different reasons and
fully tracking this, especially with stacktraces would incur extra
memory costs. As a compromise, store and print the migrate_reason of
the last migration that occurred to the page. This is enough to
distinguish compaction, numa balancing etc.Example page_owner entry after the patch:
Page allocated via order 0, mask 0x24200ca(GFP_HIGHUSER_MOVABLE)
PFN 628753 type Movable Block 1228 type Movable Flags 0x1fffff80040030(dirty|lru|swapbacked)
[] __alloc_pages_nodemask+0x134/0x230
[] alloc_pages_vma+0xb5/0x250
[] shmem_alloc_page+0x61/0x90
[] shmem_getpage_gfp+0x678/0x960
[] shmem_fallocate+0x329/0x440
[] vfs_fallocate+0x140/0x230
[] SyS_fallocate+0x44/0x70
[] entry_SYSCALL_64_fastpath+0x12/0x71
Page has been migrated, last migrate reason: compactionSigned-off-by: Vlastimil Babka
Cc: Joonsoo Kim
Cc: Minchan Kim
Cc: Sasha Levin
Cc: "Kirill A. Shutemov"
Cc: Mel Gorman
Cc: Michal Hocko
Cc: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The page_owner mechanism stores gfp_flags of an allocation and stack
trace that lead to it. During page migration, the original information
is practically replaced by the allocation of free page as the migration
target. Arguably this is less useful and might lead to all the
page_owner info for migratable pages gradually converge towards
compaction or numa balancing migrations. It has also lead to
inaccuracies such as one fixed by commit e2cfc91120fa ("mm/page_owner:
set correct gfp_mask on page_owner").This patch thus introduces copying the page_owner info during migration.
However, since the fact that the page has been migrated from its
original place might be useful for debugging, the next patch will
introduce a way to track that information as well.Signed-off-by: Vlastimil Babka
Acked-by: Michal Hocko
Cc: Joonsoo Kim
Cc: Minchan Kim
Cc: Sasha Levin
Cc: "Kirill A. Shutemov"
Cc: Mel Gorman
Cc: Hugh Dickins
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
CONFIG_PAGE_OWNER attempts to impose negligible runtime overhead when
enabled during compilation, but not actually enabled during runtime by
boot param page_owner=on. This overhead can be further reduced using
the static key mechanism, which this patch does.Signed-off-by: Vlastimil Babka
Acked-by: Michal Hocko
Cc: Joonsoo Kim
Cc: Minchan Kim
Cc: Sasha Levin
Cc: "Kirill A. Shutemov"
Cc: Mel Gorman
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
The information in /sys/kernel/debug/page_owner includes the migratetype
of the pageblock the page belongs to. This is also checked against the
page's migratetype (as declared by gfp_flags during its allocation), and
the page is reported as Fallback if its migratetype differs from the
pageblock's one. t This is somewhat misleading because in fact fallback
allocation is not the only reason why these two can differ. It also
doesn't direcly provide the page's migratetype, although it's possible
to derive that from the gfp_flags.It's arguably better to print both page and pageblock's migratetype and
leave the interpretation to the consumer than to suggest fallback
allocation as the only possible reason. While at it, we can print the
migratetypes as string the same way as /proc/pagetypeinfo does, as some
of the numeric values depend on kernel configuration. For that, this
patch moves the migratetype_names array from #ifdef CONFIG_PROC_FS part
of mm/vmstat.c to mm/page_alloc.c and exports it.With the new format strings for flags, we can now also provide symbolic
page and gfp flags in the /sys/kernel/debug/page_owner file. This
replaces the positional printing of page flags as single letters, which
might have looked nicer, but was limited to a subset of flags, and
required the user to remember the letters.Example page_owner entry after the patch:
Page allocated via order 0, mask 0x24213ca(GFP_HIGHUSER_MOVABLE|__GFP_COLD|__GFP_NOWARN|__GFP_NORETRY)
PFN 520 type Movable Block 1 type Movable Flags 0xfffff8001006c(referenced|uptodate|lru|active|mappedtodisk)
[] __alloc_pages_nodemask+0x134/0x230
[] alloc_pages_current+0x88/0x120
[] __page_cache_alloc+0xe6/0x120
[] __do_page_cache_readahead+0xdc/0x240
[] ondemand_readahead+0x135/0x260
[] page_cache_sync_readahead+0x31/0x50
[] generic_file_read_iter+0x453/0x760
[] __vfs_read+0xa7/0xd0Signed-off-by: Vlastimil Babka
Acked-by: Michal Hocko
Cc: Joonsoo Kim
Cc: Minchan Kim
Cc: Sasha Levin
Cc: "Kirill A. Shutemov"
Cc: Mel Gorman
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
18 Jul, 2015
1 commit
-
Currently, we set wrong gfp_mask to page_owner info in case of isolated
freepage by compaction and split page. It causes incorrect mixed
pageblock report that we can get from '/proc/pagetypeinfo'. This metric
is really useful to measure fragmentation effect so should be accurate.
This patch fixes it by setting correct information.Without this patch, after kernel build workload is finished, number of
mixed pageblock is 112 among roughly 210 movable pageblocks.But, with this fix, output shows that mixed pageblock is just 57.
Signed-off-by: Joonsoo Kim
Cc: Mel Gorman
Cc: Vlastimil Babka
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
17 Jun, 2015
1 commit
-
This was using module_init, but there is no way this code can
be modular. In the non-modular case, a module_init becomes a
device_initcall, but this really isn't a device. So we should
choose a more appropriate initcall bucket to put it in.In order of execution, our close choices are:
fs_initcall(fn)
rootfs_initcall(fn)
device_initcall(fn)
late_initcall(fn)..and since the initcall here goes after debugfs, we really
should be post-rootfs, which means late_initcall makes the
most sense here.Cc: Andrew Morton
Cc: linux-mm@kvack.org
Signed-off-by: Paul Gortmaker
12 Feb, 2015
1 commit
-
Page owner uses the page_ext structure to keep meta-information for every
page in the system. The structure also contains a field of type 'struct
stack_trace', page owner uses this field during invocation of the function
save_stack_trace. It is easy to notice that keeping a copy of this
structure for every page in the system is very inefficiently in terms of
memory.The patch removes this unnecessary field of page_ext and forces page owner
to use a stack_trace structure allocated on the stack.[akpm@linux-foundation.org: use struct initializers]
Signed-off-by: Sergei Rogachev
Acked-by: Joonsoo Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds
14 Dec, 2014
2 commits
-
Extended memory to store page owner information is initialized some time
later than that page allocator starts. Until initialization, many pages
can be allocated and they have no owner information. This make debugging
using page owner harder, so some fixup will be helpful.This patch fixes up this situation by setting fake owner information
immediately after page extension is initialized. Information doesn't tell
the right owner, but, at least, it can tell whether page is allocated or
not, more correctly.On my testing, this patch catches 13343 early allocated pages, although
they are mostly allocated from page extension feature. Anyway, after
then, there is no page left that it is allocated and has no page owner
flag.Signed-off-by: Joonsoo Kim
Cc: Mel Gorman
Cc: Johannes Weiner
Cc: Minchan Kim
Cc: Dave Hansen
Cc: Michal Nazarewicz
Cc: Jungsoo Son
Cc: Ingo Molnar
Cc: Joonsoo Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds -
This is the page owner tracking code which is introduced so far ago. It
is resident on Andrew's tree, though, nobody tried to upstream so it
remain as is. Our company uses this feature actively to debug memory leak
or to find a memory hogger so I decide to upstream this feature.This functionality help us to know who allocates the page. When
allocating a page, we store some information about allocation in extra
memory. Later, if we need to know status of all pages, we can get and
analyze it from this stored information.In previous version of this feature, extra memory is statically defined in
struct page, but, in this version, extra memory is allocated outside of
struct page. It enables us to turn on/off this feature at boottime
without considerable memory waste.Although we already have tracepoint for tracing page allocation/free,
using it to analyze page owner is rather complex. We need to enlarge the
trace buffer for preventing overlapping until userspace program launched.
And, launched program continually dump out the trace buffer for later
analysis and it would change system behaviour with more possibility rather
than just keeping it in memory, so bad for debug.Moreover, we can use page_owner feature further for various purposes. For
example, we can use it for fragmentation statistics implemented in this
patch. And, I also plan to implement some CMA failure debugging feature
using this interface.I'd like to give the credit for all developers contributed this feature,
but, it's not easy because I don't know exact history. Sorry about that.
Below is people who has "Signed-off-by" in the patches in Andrew's tree.Contributor:
Alexander Nyberg
Mel Gorman
Dave Hansen
Minchan Kim
Michal Nazarewicz
Andrew Morton
Jungsoo SonSigned-off-by: Joonsoo Kim
Cc: Mel Gorman
Cc: Johannes Weiner
Cc: Minchan Kim
Cc: Dave Hansen
Cc: Michal Nazarewicz
Cc: Jungsoo Son
Cc: Ingo Molnar
Cc: Joonsoo Kim
Signed-off-by: Andrew Morton
Signed-off-by: Linus Torvalds