linux-stable.git/kernel/power/snapshot.c, branch v6.7 Linux kernel stable tree Merge back earlier system-wide PM changes for v6.7. 2023-10-09T13:02:59+00:00 Rafael J. Wysocki rafael.j.wysocki@intel.com 2023-10-09T13:02:59+00:00 ffc843fc9c7a407474c5ebcd5dce63bcbfc0f7c0 






PM: hibernate: Fix copying the zero bitmap to safe pages
2023-10-04T18:43:44+00:00

Pavankumar Kondeti
quic_pkondeti@quicinc.com

2023-10-04T05:01:15+00:00

b21f18ef964b2c71aa0b451df6d17b7bcad8280d

The following crash is observed 100% of the time during resume from
the hibernation on a x86 QEMU system.

[   12.931887]  ? __die_body+0x1a/0x60
[   12.932324]  ? page_fault_oops+0x156/0x420
[   12.932824]  ? search_exception_tables+0x37/0x50
[   12.933389]  ? fixup_exception+0x21/0x300
[   12.933889]  ? exc_page_fault+0x69/0x150
[   12.934371]  ? asm_exc_page_fault+0x26/0x30
[   12.934869]  ? get_buffer.constprop.0+0xac/0x100
[   12.935428]  snapshot_write_next+0x7c/0x9f0
[   12.935929]  ? submit_bio_noacct_nocheck+0x2c2/0x370
[   12.936530]  ? submit_bio_noacct+0x44/0x2c0
[   12.937035]  ? hib_submit_io+0xa5/0x110
[   12.937501]  load_image+0x83/0x1a0
[   12.937919]  swsusp_read+0x17f/0x1d0
[   12.938355]  ? create_basic_memory_bitmaps+0x1b7/0x240
[   12.938967]  load_image_and_restore+0x45/0xc0
[   12.939494]  software_resume+0x13c/0x180
[   12.939994]  resume_store+0xa3/0x1d0

The commit being fixed introduced a bug in copying the zero bitmap
to safe pages. A temporary bitmap is allocated with PG_ANY flag in
prepare_image() to make a copy of zero bitmap after the unsafe pages
are marked. Freeing this temporary bitmap with PG_UNSAFE_KEEP later
results in an inconsistent state of unsafe pages. Since free bit is
left as is for this temporary bitmap after free, these pages are
treated as unsafe pages when they are allocated again. This results
in incorrect calculation of the number of pages pre-allocated for the
image.

nr_pages = (nr_zero_pages + nr_copy_pages) - nr_highmem - allocated_unsafe_pages;

The allocate_unsafe_pages is estimated to be higher than the actual
which results in running short of pages in safe_pages_list. Hence the
crash is observed in get_buffer() due to NULL pointer access of
safe_pages_list.

Fix this issue by creating the temporary zero bitmap from safe pages
(free bit not set) so that the corresponding free bits can be cleared
while freeing this bitmap.

Fixes: 005e8dddd497 ("PM: hibernate: don't store zero pages in the image file")
Suggested-by:: Brian Geffon <bgeffon@google.com>
Signed-off-by: Pavankumar Kondeti <quic_pkondeti@quicinc.com>
Reviewed-by: Brian Geffon <bgeffon@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>





The following crash is observed 100% of the time during resume from
the hibernation on a x86 QEMU system.

[   12.931887]  ? __die_body+0x1a/0x60
[   12.932324]  ? page_fault_oops+0x156/0x420
[   12.932824]  ? search_exception_tables+0x37/0x50
[   12.933389]  ? fixup_exception+0x21/0x300
[   12.933889]  ? exc_page_fault+0x69/0x150
[   12.934371]  ? asm_exc_page_fault+0x26/0x30
[   12.934869]  ? get_buffer.constprop.0+0xac/0x100
[   12.935428]  snapshot_write_next+0x7c/0x9f0
[   12.935929]  ? submit_bio_noacct_nocheck+0x2c2/0x370
[   12.936530]  ? submit_bio_noacct+0x44/0x2c0
[   12.937035]  ? hib_submit_io+0xa5/0x110
[   12.937501]  load_image+0x83/0x1a0
[   12.937919]  swsusp_read+0x17f/0x1d0
[   12.938355]  ? create_basic_memory_bitmaps+0x1b7/0x240
[   12.938967]  load_image_and_restore+0x45/0xc0
[   12.939494]  software_resume+0x13c/0x180
[   12.939994]  resume_store+0xa3/0x1d0

The commit being fixed introduced a bug in copying the zero bitmap
to safe pages. A temporary bitmap is allocated with PG_ANY flag in
prepare_image() to make a copy of zero bitmap after the unsafe pages
are marked. Freeing this temporary bitmap with PG_UNSAFE_KEEP later
results in an inconsistent state of unsafe pages. Since free bit is
left as is for this temporary bitmap after free, these pages are
treated as unsafe pages when they are allocated again. This results
in incorrect calculation of the number of pages pre-allocated for the
image.

nr_pages = (nr_zero_pages + nr_copy_pages) - nr_highmem - allocated_unsafe_pages;

The allocate_unsafe_pages is estimated to be higher than the actual
which results in running short of pages in safe_pages_list. Hence the
crash is observed in get_buffer() due to NULL pointer access of
safe_pages_list.

Fix this issue by creating the temporary zero bitmap from safe pages
(free bit not set) so that the corresponding free bits can be cleared
while freeing this bitmap.

Fixes: 005e8dddd497 ("PM: hibernate: don't store zero pages in the image file")
Suggested-by:: Brian Geffon <bgeffon@google.com>
Signed-off-by: Pavankumar Kondeti <quic_pkondeti@quicinc.com>
Reviewed-by: Brian Geffon <bgeffon@google.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>







PM: hibernate: Clean up sync_read handling in snapshot_write_next()
2023-09-26T18:21:28+00:00

Brian Geffon
bgeffon@google.com

2023-09-22T16:07:04+00:00

d08970df1980476f27936e24d452550f3e9e92e1

In snapshot_write_next(), sync_read is set and unset in three different
spots unnecessiarly. As a result there is a subtle bug where the first
page after the meta data has been loaded unconditionally sets sync_read
to 0. If this first PFN was actually a highmem page, then the returned
buffer will be the global "buffer," and the page needs to be loaded
synchronously.

That is, I'm not sure we can always assume the following to be safe:

	handle->buffer = get_buffer(&orig_bm, &ca);
	handle->sync_read = 0;

Because get_buffer() can call get_highmem_page_buffer() which can
return 'buffer'.

The easiest way to address this is just set sync_read before
snapshot_write_next() returns if handle->buffer == buffer.

Signed-off-by: Brian Geffon <bgeffon@google.com>
Fixes: 8357376d3df2 ("[PATCH] swsusp: Improve handling of highmem")
Cc: All applicable <stable@vger.kernel.org>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>





In snapshot_write_next(), sync_read is set and unset in three different
spots unnecessiarly. As a result there is a subtle bug where the first
page after the meta data has been loaded unconditionally sets sync_read
to 0. If this first PFN was actually a highmem page, then the returned
buffer will be the global "buffer," and the page needs to be loaded
synchronously.

That is, I'm not sure we can always assume the following to be safe:

	handle->buffer = get_buffer(&orig_bm, &ca);
	handle->sync_read = 0;

Because get_buffer() can call get_highmem_page_buffer() which can
return 'buffer'.

The easiest way to address this is just set sync_read before
snapshot_write_next() returns if handle->buffer == buffer.

Signed-off-by: Brian Geffon <bgeffon@google.com>
Fixes: 8357376d3df2 ("[PATCH] swsusp: Improve handling of highmem")
Cc: All applicable <stable@vger.kernel.org>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>







PM: hibernate: Use __get_safe_page() rather than touching the list
2023-09-21T18:25:49+00:00

Brian Geffon
bgeffon@google.com

2023-09-21T17:00:45+00:00

f0c7183008b41e92fa676406d87f18773724b48b

We found at least one situation where the safe pages list was empty and
get_buffer() would gladly try to use a NULL pointer.

Signed-off-by: Brian Geffon <bgeffon@google.com>
Fixes: 8357376d3df2 ("[PATCH] swsusp: Improve handling of highmem")
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>





We found at least one situation where the safe pages list was empty and
get_buffer() would gladly try to use a NULL pointer.

Signed-off-by: Brian Geffon <bgeffon@google.com>
Fixes: 8357376d3df2 ("[PATCH] swsusp: Improve handling of highmem")
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>







PM: hibernate: don't store zero pages in the image file
2023-07-24T07:51:59+00:00

Brian Geffon
bgeffon@google.com

2023-07-14T17:55:05+00:00

005e8dddd4978f6243820d031987056a1a88a2dd

On ChromeOS we've observed a considerable number of in-use pages filled with
zeros. Today with hibernate it's entirely possible that saveable pages are just
zero filled. Since we're already copying pages word-by-word in do_copy_page it
becomes almost free to determine if a page was completely filled with zeros.

This change introduces a new bitmap which will track these zero pages. If a page
is zero it will not be included in the saved image, instead to track these zero
pages in the image file we will introduce a new flag which we will set on the
packed PFN list. When reading back in the image file we will detect these zero
page PFNs and rebuild the zero page bitmap.

When the image is being loaded through calls to write_next_page if we encounter
a zero page we will silently memset it to 0 and then continue on to the next
page. Given the implementation in snapshot_read_next/snapshot_write_next this
change  will be transparent to non-compressed/compressed and swsusp modes of
operation.

To provide some concrete numbers from simple ad-hoc testing, on a device which
was lightly in use we saw that:

PM: hibernation: Image created (964408 pages copied, 548304 zero pages)

Of the approximately 6.2GB of saveable pages 2.2GB (36%) were just zero filled
and could be tracked entirely within the packed PFN list. The savings would
obviously be much lower for lzo compressed images, but even in the case of
compression not copying pages across to the compression threads will still
speed things up. It's also possible that we would see better overall compression
ratios as larger regions of "real data" would improve the compressibility.

Finally, such an approach could dramatically improve swsusp performance
as each one of those zero pages requires a write syscall to reload, by
handling it as part of the packed PFN list we're able to fully avoid
that.

Signed-off-by: Brian Geffon <bgeffon@google.com>
[ rjw: Whitespace adjustments, removal of redundant parentheses ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>





On ChromeOS we've observed a considerable number of in-use pages filled with
zeros. Today with hibernate it's entirely possible that saveable pages are just
zero filled. Since we're already copying pages word-by-word in do_copy_page it
becomes almost free to determine if a page was completely filled with zeros.

This change introduces a new bitmap which will track these zero pages. If a page
is zero it will not be included in the saved image, instead to track these zero
pages in the image file we will introduce a new flag which we will set on the
packed PFN list. When reading back in the image file we will detect these zero
page PFNs and rebuild the zero page bitmap.

When the image is being loaded through calls to write_next_page if we encounter
a zero page we will silently memset it to 0 and then continue on to the next
page. Given the implementation in snapshot_read_next/snapshot_write_next this
change  will be transparent to non-compressed/compressed and swsusp modes of
operation.

To provide some concrete numbers from simple ad-hoc testing, on a device which
was lightly in use we saw that:

PM: hibernation: Image created (964408 pages copied, 548304 zero pages)

Of the approximately 6.2GB of saveable pages 2.2GB (36%) were just zero filled
and could be tracked entirely within the packed PFN list. The savings would
obviously be much lower for lzo compressed images, but even in the case of
compression not copying pages across to the compression threads will still
speed things up. It's also possible that we would see better overall compression
ratios as larger regions of "real data" would improve the compressibility.

Finally, such an approach could dramatically improve swsusp performance
as each one of those zero pages requires a write syscall to reload, by
handling it as part of the packed PFN list we're able to fully avoid
that.

Signed-off-by: Brian Geffon <bgeffon@google.com>
[ rjw: Whitespace adjustments, removal of redundant parentheses ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>







Merge tag 'mm-stable-2023-06-24-19-15' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
2023-06-28T17:28:11+00:00

Linus Torvalds
torvalds@linux-foundation.org

2023-06-28T17:28:11+00:00

6e17c6de3ddf3073741d9c91a796ee696914d8a0

Pull mm updates from Andrew Morton:

 - Yosry Ahmed brought back some cgroup v1 stats in OOM logs

 - Yosry has also eliminated cgroup's atomic rstat flushing

 - Nhat Pham adds the new cachestat() syscall. It provides userspace
   with the ability to query pagecache status - a similar concept to
   mincore() but more powerful and with improved usability

 - Mel Gorman provides more optimizations for compaction, reducing the
   prevalence of page rescanning

 - Lorenzo Stoakes has done some maintanance work on the
   get_user_pages() interface

 - Liam Howlett continues with cleanups and maintenance work to the
   maple tree code. Peng Zhang also does some work on maple tree

 - Johannes Weiner has done some cleanup work on the compaction code

 - David Hildenbrand has contributed additional selftests for
   get_user_pages()

 - Thomas Gleixner has contributed some maintenance and optimization
   work for the vmalloc code

 - Baolin Wang has provided some compaction cleanups,

 - SeongJae Park continues maintenance work on the DAMON code

 - Huang Ying has done some maintenance on the swap code's usage of
   device refcounting

 - Christoph Hellwig has some cleanups for the filemap/directio code

 - Ryan Roberts provides two patch series which yield some
   rationalization of the kernel's access to pte entries - use the
   provided APIs rather than open-coding accesses

 - Lorenzo Stoakes has some fixes to the interaction between pagecache
   and directio access to file mappings

 - John Hubbard has a series of fixes to the MM selftesting code

 - ZhangPeng continues the folio conversion campaign

 - Hugh Dickins has been working on the pagetable handling code, mainly
   with a view to reducing the load on the mmap_lock

 - Catalin Marinas has reduced the arm64 kmalloc() minimum alignment
   from 128 to 8

 - Domenico Cerasuolo has improved the zswap reclaim mechanism by
   reorganizing the LRU management

 - Matthew Wilcox provides some fixups to make gfs2 work better with the
   buffer_head code

 - Vishal Moola also has done some folio conversion work

 - Matthew Wilcox has removed the remnants of the pagevec code - their
   functionality is migrated over to struct folio_batch

* tag 'mm-stable-2023-06-24-19-15' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (380 commits)
  mm/hugetlb: remove hugetlb_set_page_subpool()
  mm: nommu: correct the range of mmap_sem_read_lock in task_mem()
  hugetlb: revert use of page_cache_next_miss()
  Revert "page cache: fix page_cache_next/prev_miss off by one"
  mm/vmscan: fix root proactive reclaim unthrottling unbalanced node
  mm: memcg: rename and document global_reclaim()
  mm: kill [add|del]_page_to_lru_list()
  mm: compaction: convert to use a folio in isolate_migratepages_block()
  mm: zswap: fix double invalidate with exclusive loads
  mm: remove unnecessary pagevec includes
  mm: remove references to pagevec
  mm: rename invalidate_mapping_pagevec to mapping_try_invalidate
  mm: remove struct pagevec
  net: convert sunrpc from pagevec to folio_batch
  i915: convert i915_gpu_error to use a folio_batch
  pagevec: rename fbatch_count()
  mm: remove check_move_unevictable_pages()
  drm: convert drm_gem_put_pages() to use a folio_batch
  i915: convert shmem_sg_free_table() to use a folio_batch
  scatterlist: add sg_set_folio()
  ...





Pull mm updates from Andrew Morton:

 - Yosry Ahmed brought back some cgroup v1 stats in OOM logs

 - Yosry has also eliminated cgroup's atomic rstat flushing

 - Nhat Pham adds the new cachestat() syscall. It provides userspace
   with the ability to query pagecache status - a similar concept to
   mincore() but more powerful and with improved usability

 - Mel Gorman provides more optimizations for compaction, reducing the
   prevalence of page rescanning

 - Lorenzo Stoakes has done some maintanance work on the
   get_user_pages() interface

 - Liam Howlett continues with cleanups and maintenance work to the
   maple tree code. Peng Zhang also does some work on maple tree

 - Johannes Weiner has done some cleanup work on the compaction code

 - David Hildenbrand has contributed additional selftests for
   get_user_pages()

 - Thomas Gleixner has contributed some maintenance and optimization
   work for the vmalloc code

 - Baolin Wang has provided some compaction cleanups,

 - SeongJae Park continues maintenance work on the DAMON code

 - Huang Ying has done some maintenance on the swap code's usage of
   device refcounting

 - Christoph Hellwig has some cleanups for the filemap/directio code

 - Ryan Roberts provides two patch series which yield some
   rationalization of the kernel's access to pte entries - use the
   provided APIs rather than open-coding accesses

 - Lorenzo Stoakes has some fixes to the interaction between pagecache
   and directio access to file mappings

 - John Hubbard has a series of fixes to the MM selftesting code

 - ZhangPeng continues the folio conversion campaign

 - Hugh Dickins has been working on the pagetable handling code, mainly
   with a view to reducing the load on the mmap_lock

 - Catalin Marinas has reduced the arm64 kmalloc() minimum alignment
   from 128 to 8

 - Domenico Cerasuolo has improved the zswap reclaim mechanism by
   reorganizing the LRU management

 - Matthew Wilcox provides some fixups to make gfs2 work better with the
   buffer_head code

 - Vishal Moola also has done some folio conversion work

 - Matthew Wilcox has removed the remnants of the pagevec code - their
   functionality is migrated over to struct folio_batch

* tag 'mm-stable-2023-06-24-19-15' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (380 commits)
  mm/hugetlb: remove hugetlb_set_page_subpool()
  mm: nommu: correct the range of mmap_sem_read_lock in task_mem()
  hugetlb: revert use of page_cache_next_miss()
  Revert "page cache: fix page_cache_next/prev_miss off by one"
  mm/vmscan: fix root proactive reclaim unthrottling unbalanced node
  mm: memcg: rename and document global_reclaim()
  mm: kill [add|del]_page_to_lru_list()
  mm: compaction: convert to use a folio in isolate_migratepages_block()
  mm: zswap: fix double invalidate with exclusive loads
  mm: remove unnecessary pagevec includes
  mm: remove references to pagevec
  mm: rename invalidate_mapping_pagevec to mapping_try_invalidate
  mm: remove struct pagevec
  net: convert sunrpc from pagevec to folio_batch
  i915: convert i915_gpu_error to use a folio_batch
  pagevec: rename fbatch_count()
  mm: remove check_move_unevictable_pages()
  drm: convert drm_gem_put_pages() to use a folio_batch
  i915: convert shmem_sg_free_table() to use a folio_batch
  scatterlist: add sg_set_folio()
  ...







mm: page_alloc: move mark_free_page() into snapshot.c
2023-06-09T23:25:24+00:00

Kefeng Wang
wangkefeng.wang@huawei.com

2023-05-16T06:38:17+00:00

31a1b9d7fe768db521b12287ec6426983e9787e3

The mark_free_page() is only used in kernel/power/snapshot.c, move it out
to reduce a bit of page_alloc.c

Link: https://lkml.kernel.org/r/20230516063821.121844-10-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>





The mark_free_page() is only used in kernel/power/snapshot.c, move it out
to reduce a bit of page_alloc.c

Link: https://lkml.kernel.org/r/20230516063821.121844-10-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Iurii Zaikin <yzaikin@google.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Len Brown <len.brown@intel.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>







PM: hibernate: Correct spelling mistake in a comment
2023-05-24T17:00:50+00:00

Wang Honghui
honghui.wang@ucas.com.cn

2023-05-04T09:18:24+00:00

847aea98e01cf084efcb84490b3060af343d1458

Fix a typo in a comment in kernel/power/snapshot.c

Signed-off-by: Wang Honghui <honghui.wang@ucas.com.cn>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>





Fix a typo in a comment in kernel/power/snapshot.c

Signed-off-by: Wang Honghui <honghui.wang@ucas.com.cn>
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>







PM: hibernate: Complain about memory map mismatches during resume
2022-12-01T18:20:14+00:00

Xueqin Luo
luoxueqin@kylinos.cn

2022-11-11T05:19:49+00:00

3363e0adb3931e987caa6404327b35ea2db231d8

The system memory map can change over a hibernation-restore cycle due
to a defect in the platform firmware, and some of the page frames used
by the kernel before hibernation may not be available any more during
the subsequent restore which leads to the error below.

[  T357] PM: Image loading progress:   0%
[  T357] PM: Read 2681596 kbytes in 0.03 seconds (89386.53 MB/s)
[  T357] PM: Error -14 resuming
[  T357] PM: Failed to load hibernation image, recovering.
[  T357] PM: Basic memory bitmaps freed
[  T357] OOM killer enabled.
[  T357] Restarting tasks ... done.
[  T357] PM: resume from hibernation failed (-14)
[  T357] PM: Hibernation image not present or could not be loaded.

Add an error message to the unpack() function to allow problematic
page frames to be identified and the source of the problem to be
diagnosed more easily. This can save developers quite a bit of
debugging time.

Signed-off-by: Xueqin Luo <luoxueqin@kylinos.cn>
[ rjw: New subject, edited changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>





The system memory map can change over a hibernation-restore cycle due
to a defect in the platform firmware, and some of the page frames used
by the kernel before hibernation may not be available any more during
the subsequent restore which leads to the error below.

[  T357] PM: Image loading progress:   0%
[  T357] PM: Read 2681596 kbytes in 0.03 seconds (89386.53 MB/s)
[  T357] PM: Error -14 resuming
[  T357] PM: Failed to load hibernation image, recovering.
[  T357] PM: Basic memory bitmaps freed
[  T357] OOM killer enabled.
[  T357] Restarting tasks ... done.
[  T357] PM: resume from hibernation failed (-14)
[  T357] PM: Hibernation image not present or could not be loaded.

Add an error message to the unpack() function to allow problematic
page frames to be identified and the source of the problem to be
diagnosed more easily. This can save developers quite a bit of
debugging time.

Signed-off-by: Xueqin Luo <luoxueqin@kylinos.cn>
[ rjw: New subject, edited changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>







PM: hibernate: Fix mistake in kerneldoc comment
2022-11-03T16:32:58+00:00

xiongxin
xiongxin@kylinos.cn

2022-11-01T02:28:39+00:00

6e5d7300cbe7c3541bc31f16db3e9266e6027b4b

The actual maximum image size formula in hibernate_preallocate_memory()
is as follows:

max_size = (count - (size + PAGES_FOR_IO)) / 2
	    - 2 * DIV_ROUND_UP(reserved_size, PAGE_SIZE);

but the one in the kerneldoc comment of the function is different and
incorrect.

Fixes: ddeb64870810 ("PM / Hibernate: Add sysfs knob to control size of memory for drivers")
Signed-off-by: xiongxin <xiongxin@kylinos.cn>
[ rjw: Subject and changelog rewrite ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>





The actual maximum image size formula in hibernate_preallocate_memory()
is as follows:

max_size = (count - (size + PAGES_FOR_IO)) / 2
	    - 2 * DIV_ROUND_UP(reserved_size, PAGE_SIZE);

but the one in the kerneldoc comment of the function is different and
incorrect.

Fixes: ddeb64870810 ("PM / Hibernate: Add sysfs knob to control size of memory for drivers")
Signed-off-by: xiongxin <xiongxin@kylinos.cn>
[ rjw: Subject and changelog rewrite ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>