linux-stable.git/kernel/power/snapshot.c, branch v6.15

PM: hibernate: Replace deprecated kmap_atomic() with kmap_local_page()

2025-02-18T19:39:24+00:00

kmap_atomic() is deprecated and should be replaced with kmap_local_page()
[1][2]. kmap_local_page() is faster in kernels with HIGHMEM enabled, can
take page faults, and allows preemption.

According to [2], this replacement is safe as long as the code between
kmap_atomic() and kunmap_atomic() does not implicitly depend on disabling
page faults or preemption. In all of the call sites in this patch, the only
thing happening between mapping and unmapping pages is copy_page() calls,
and I don't suspect they depend on disabling page faults or preemption.

Link: https://lwn.net/Articles/836144/ [1]
Link: https://docs.kernel.org/mm/highmem.html#temporary-virtual-mappings [2]
Signed-off-by: David Reaver 
Link: https://patch.msgid.link/20250112152658.20132-1-me@davidreaver.com
Signed-off-by: Rafael J. Wysocki

mm/memblock: add memblock_alloc_or_panic interface

2025-01-26T04:22:38+00:00

Before SLUB initialization, various subsystems used memblock_alloc to
allocate memory.  In most cases, when memory allocation fails, an
immediate panic is required.  To simplify this behavior and reduce
repetitive checks, introduce `memblock_alloc_or_panic`.  This function
ensures that memory allocation failures result in a panic automatically,
improving code readability and consistency across subsystems that require
this behavior.

[guoweikang.kernel@gmail.com: arch/s390: save_area_alloc default failure behavior changed to panic]
  Link: https://lkml.kernel.org/r/20250109033136.2845676-1-guoweikang.kernel@gmail.com
  Link: https://lore.kernel.org/lkml/Z2fknmnNtiZbCc7x@kernel.org/
Link: https://lkml.kernel.org/r/20250102072528.650926-1-guoweikang.kernel@gmail.com
Signed-off-by: Guo Weikang 
Acked-by: Geert Uytterhoeven 	[m68k]
Reviewed-by: Alexander Gordeev 	[s390]
Acked-by: Mike Rapoport (Microsoft) 
Cc: Alexander Gordeev 
Signed-off-by: Andrew Morton

PM: hibernate: Remove unused stub for saveable_highmem_page()

2024-09-10T18:11:40+00:00

When saveable_highmem_page() is unused, it prevents kernel builds
with clang, `make W=1` and CONFIG_WERROR=y:

kernel/power/snapshot.c:1369:21: error: unused function 'saveable_highmem_page' [-Werror,-Wunused-function]
 1369 | static inline void *saveable_highmem_page(struct zone *z, unsigned long p)
      |                     ^~~~~~~~~~~~~~~~~~~~~

Fix this by removing unused stub.

See also commit 6863f5643dd7 ("kbuild: allow Clang to find unused static
inline functions for W=1 build").

Signed-off-by: Andy Shevchenko 
Link: https://patch.msgid.link/20240905184848.318978-1-andriy.shevchenko@linux.intel.com
Signed-off-by: Rafael J. Wysocki

PM: hibernate: Don't ignore return from set_memory_ro()

2024-02-22T19:08:03+00:00

set_memory_ro() and set_memory_rw() can fail, leaving memory
unprotected.

Take the returned value into account and abort in case of
failure.

Signed-off-by: Christophe Leroy 
Reviewed-by: Kees Cook 
Signed-off-by: Rafael J. Wysocki

PM: hibernate: Use kmap_local_page() in copy_data_page()

2023-12-19T19:55:16+00:00

kmap_atomic() has been deprecated in favor of kmap_local_page().

kmap_atomic() disables page-faults and preemption (the latter
only for !PREEMPT_RT kernels).The code between the mapping and
un-mapping in this patch does not depend on the above-mentioned
side effects.So simply replaced kmap_atomic() with kmap_local_page().

Signed-off-by: Chen Haonan 
[ rjw: Subject edits ]
Signed-off-by: Rafael J. Wysocki

PM: hibernate: Do not initialize error in snapshot_write_next()

2023-12-11T21:09:52+00:00

The error variable in snapshot_write_next() gets a value before it is
used, so don't initialize it to 0 upfront.

Signed-off-by: Li zeming 
[ rjw: Subject and changelog rewrite ]
Signed-off-by: Rafael J. Wysocki

PM: hibernate: Drop unnecessary local variable initialization

2023-12-11T21:02:48+00:00

It is not necessary to intialize the error variable in
create_basic_memory_bitmaps(), because it is only read after
being assigned a value.

Signed-off-by: Wang chaodong 
[ rjw: Subject and changelog rewrite ]
Signed-off-by: Rafael J. Wysocki

Merge back earlier system-wide PM changes for v6.7.

2023-10-09T13:02:59+00:00

PM: hibernate: Fix copying the zero bitmap to safe pages

2023-10-04T18:43:44+00:00

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 
Signed-off-by: Pavankumar Kondeti 
Reviewed-by: Brian Geffon 
Signed-off-by: Rafael J. Wysocki

PM: hibernate: Clean up sync_read handling in snapshot_write_next()

2023-09-26T18:21:28+00:00

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 
Fixes: 8357376d3df2 ("[PATCH] swsusp: Improve handling of highmem")
Cc: All applicable 
[ rjw: Subject and changelog edits ]
Signed-off-by: Rafael J. Wysocki