<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux-stable.git/drivers/video/fbdev/core, branch v6.15</title>
<subtitle>Linux kernel stable tree</subtitle>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/'/>
<entry>
<title>Merge tag 'mm-stable-2025-03-30-16-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2025-04-01T16:29:18+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2025-04-01T16:29:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=eb0ece16027f8223d5dc9aaf90124f70577bd22a'/>
<id>eb0ece16027f8223d5dc9aaf90124f70577bd22a</id>
<content type='text'>
Pull MM updates from Andrew Morton:

 - The series "Enable strict percpu address space checks" from Uros
   Bizjak uses x86 named address space qualifiers to provide
   compile-time checking of percpu area accesses.

   This has caused a small amount of fallout - two or three issues were
   reported. In all cases the calling code was found to be incorrect.

 - The series "Some cleanup for memcg" from Chen Ridong implements some
   relatively monir cleanups for the memcontrol code.

 - The series "mm: fixes for device-exclusive entries (hmm)" from David
   Hildenbrand fixes a boatload of issues which David found then using
   device-exclusive PTE entries when THP is enabled. More work is
   needed, but this makes thins better - our own HMM selftests now
   succeed.

 - The series "mm: zswap: remove z3fold and zbud" from Yosry Ahmed
   remove the z3fold and zbud implementations. They have been deprecated
   for half a year and nobody has complained.

 - The series "mm: further simplify VMA merge operation" from Lorenzo
   Stoakes implements numerous simplifications in this area. No runtime
   effects are anticipated.

 - The series "mm/madvise: remove redundant mmap_lock operations from
   process_madvise()" from SeongJae Park rationalizes the locking in the
   madvise() implementation. Performance gains of 20-25% were observed
   in one MADV_DONTNEED microbenchmark.

 - The series "Tiny cleanup and improvements about SWAP code" from
   Baoquan He contains a number of touchups to issues which Baoquan
   noticed when working on the swap code.

 - The series "mm: kmemleak: Usability improvements" from Catalin
   Marinas implements a couple of improvements to the kmemleak
   user-visible output.

 - The series "mm/damon/paddr: fix large folios access and schemes
   handling" from Usama Arif provides a couple of fixes for DAMON's
   handling of large folios.

 - The series "mm/damon/core: fix wrong and/or useless damos_walk()
   behaviors" from SeongJae Park fixes a few issues with the accuracy of
   kdamond's walking of DAMON regions.

 - The series "expose mapping wrprotect, fix fb_defio use" from Lorenzo
   Stoakes changes the interaction between framebuffer deferred-io and
   core MM. No functional changes are anticipated - this is preparatory
   work for the future removal of page structure fields.

 - The series "mm/damon: add support for hugepage_size DAMOS filter"
   from Usama Arif adds a DAMOS filter which permits the filtering by
   huge page sizes.

 - The series "mm: permit guard regions for file-backed/shmem mappings"
   from Lorenzo Stoakes extends the guard region feature from its
   present "anon mappings only" state. The feature now covers shmem and
   file-backed mappings.

 - The series "mm: batched unmap lazyfree large folios during
   reclamation" from Barry Song cleans up and speeds up the unmapping
   for pte-mapped large folios.

 - The series "reimplement per-vma lock as a refcount" from Suren
   Baghdasaryan puts the vm_lock back into the vma. Our reasons for
   pulling it out were largely bogus and that change made the code more
   messy. This patchset provides small (0-10%) improvements on one
   microbenchmark.

 - The series "Docs/mm/damon: misc DAMOS filters documentation fixes and
   improves" from SeongJae Park does some maintenance work on the DAMON
   docs.

 - The series "hugetlb/CMA improvements for large systems" from Frank
   van der Linden addresses a pile of issues which have been observed
   when using CMA on large machines.

 - The series "mm/damon: introduce DAMOS filter type for unmapped pages"
   from SeongJae Park enables users of DMAON/DAMOS to filter my the
   page's mapped/unmapped status.

 - The series "zsmalloc/zram: there be preemption" from Sergey
   Senozhatsky teaches zram to run its compression and decompression
   operations preemptibly.

 - The series "selftests/mm: Some cleanups from trying to run them" from
   Brendan Jackman fixes a pile of unrelated issues which Brendan
   encountered while runnimg our selftests.

 - The series "fs/proc/task_mmu: add guard region bit to pagemap" from
   Lorenzo Stoakes permits userspace to use /proc/pid/pagemap to
   determine whether a particular page is a guard page.

 - The series "mm, swap: remove swap slot cache" from Kairui Song
   removes the swap slot cache from the allocation path - it simply
   wasn't being effective.

 - The series "mm: cleanups for device-exclusive entries (hmm)" from
   David Hildenbrand implements a number of unrelated cleanups in this
   code.

 - The series "mm: Rework generic PTDUMP configs" from Anshuman Khandual
   implements a number of preparatoty cleanups to the GENERIC_PTDUMP
   Kconfig logic.

 - The series "mm/damon: auto-tune aggregation interval" from SeongJae
   Park implements a feedback-driven automatic tuning feature for
   DAMON's aggregation interval tuning.

 - The series "Fix lazy mmu mode" from Ryan Roberts fixes some issues in
   powerpc, sparc and x86 lazy MMU implementations. Ryan did this in
   preparation for implementing lazy mmu mode for arm64 to optimize
   vmalloc.

 - The series "mm/page_alloc: Some clarifications for migratetype
   fallback" from Brendan Jackman reworks some commentary to make the
   code easier to follow.

 - The series "page_counter cleanup and size reduction" from Shakeel
   Butt cleans up the page_counter code and fixes a size increase which
   we accidentally added late last year.

 - The series "Add a command line option that enables control of how
   many threads should be used to allocate huge pages" from Thomas
   Prescher does that. It allows the careful operator to significantly
   reduce boot time by tuning the parallalization of huge page
   initialization.

 - The series "Fix calculations in trace_balance_dirty_pages() for cgwb"
   from Tang Yizhou fixes the tracing output from the dirty page
   balancing code.

 - The series "mm/damon: make allow filters after reject filters useful
   and intuitive" from SeongJae Park improves the handling of allow and
   reject filters. Behaviour is made more consistent and the documention
   is updated accordingly.

 - The series "Switch zswap to object read/write APIs" from Yosry Ahmed
   updates zswap to the new object read/write APIs and thus permits the
   removal of some legacy code from zpool and zsmalloc.

 - The series "Some trivial cleanups for shmem" from Baolin Wang does as
   it claims.

 - The series "fs/dax: Fix ZONE_DEVICE page reference counts" from
   Alistair Popple regularizes the weird ZONE_DEVICE page refcount
   handling in DAX, permittig the removal of a number of special-case
   checks.

 - The series "refactor mremap and fix bug" from Lorenzo Stoakes is a
   preparatoty refactoring and cleanup of the mremap() code.

 - The series "mm: MM owner tracking for large folios (!hugetlb) +
   CONFIG_NO_PAGE_MAPCOUNT" from David Hildenbrand reworks the manner in
   which we determine whether a large folio is known to be mapped
   exclusively into a single MM.

 - The series "mm/damon: add sysfs dirs for managing DAMOS filters based
   on handling layers" from SeongJae Park adds a couple of new sysfs
   directories to ease the management of DAMON/DAMOS filters.

 - The series "arch, mm: reduce code duplication in mem_init()" from
   Mike Rapoport consolidates many per-arch implementations of
   mem_init() into code generic code, where that is practical.

 - The series "mm/damon/sysfs: commit parameters online via
   damon_call()" from SeongJae Park continues the cleaning up of sysfs
   access to DAMON internal data.

 - The series "mm: page_ext: Introduce new iteration API" from Luiz
   Capitulino reworks the page_ext initialization to fix a boot-time
   crash which was observed with an unusual combination of compile and
   cmdline options.

 - The series "Buddy allocator like (or non-uniform) folio split" from
   Zi Yan reworks the code to split a folio into smaller folios. The
   main benefit is lessened memory consumption: fewer post-split folios
   are generated.

 - The series "Minimize xa_node allocation during xarry split" from Zi
   Yan reduces the number of xarray xa_nodes which are generated during
   an xarray split.

 - The series "drivers/base/memory: Two cleanups" from Gavin Shan
   performs some maintenance work on the drivers/base/memory code.

 - The series "Add tracepoints for lowmem reserves, watermarks and
   totalreserve_pages" from Martin Liu adds some more tracepoints to the
   page allocator code.

 - The series "mm/madvise: cleanup requests validations and
   classifications" from SeongJae Park cleans up some warts which
   SeongJae observed during his earlier madvise work.

 - The series "mm/hwpoison: Fix regressions in memory failure handling"
   from Shuai Xue addresses two quite serious regressions which Shuai
   has observed in the memory-failure implementation.

 - The series "mm: reliable huge page allocator" from Johannes Weiner
   makes huge page allocations cheaper and more reliable by reducing
   fragmentation.

 - The series "Minor memcg cleanups &amp; prep for memdescs" from Matthew
   Wilcox is preparatory work for the future implementation of memdescs.

 - The series "track memory used by balloon drivers" from Nico Pache
   introduces a way to track memory used by our various balloon drivers.

 - The series "mm/damon: introduce DAMOS filter type for active pages"
   from Nhat Pham permits users to filter for active/inactive pages,
   separately for file and anon pages.

 - The series "Adding Proactive Memory Reclaim Statistics" from Hao Jia
   separates the proactive reclaim statistics from the direct reclaim
   statistics.

 - The series "mm/vmscan: don't try to reclaim hwpoison folio" from
   Jinjiang Tu fixes our handling of hwpoisoned pages within the reclaim
   code.

* tag 'mm-stable-2025-03-30-16-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (431 commits)
  mm/page_alloc: remove unnecessary __maybe_unused in order_to_pindex()
  x86/mm: restore early initialization of high_memory for 32-bits
  mm/vmscan: don't try to reclaim hwpoison folio
  mm/hwpoison: introduce folio_contain_hwpoisoned_page() helper
  cgroup: docs: add pswpin and pswpout items in cgroup v2 doc
  mm: vmscan: split proactive reclaim statistics from direct reclaim statistics
  selftests/mm: speed up split_huge_page_test
  selftests/mm: uffd-unit-tests support for hugepages &gt; 2M
  docs/mm/damon/design: document active DAMOS filter type
  mm/damon: implement a new DAMOS filter type for active pages
  fs/dax: don't disassociate zero page entries
  MM documentation: add "Unaccepted" meminfo entry
  selftests/mm: add commentary about 9pfs bugs
  fork: use __vmalloc_node() for stack allocation
  docs/mm: Physical Memory: Populate the "Zones" section
  xen: balloon: update the NR_BALLOON_PAGES state
  hv_balloon: update the NR_BALLOON_PAGES state
  balloon_compaction: update the NR_BALLOON_PAGES state
  meminfo: add a per node counter for balloon drivers
  mm: remove references to folio in __memcg_kmem_uncharge_page()
  ...
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Pull MM updates from Andrew Morton:

 - The series "Enable strict percpu address space checks" from Uros
   Bizjak uses x86 named address space qualifiers to provide
   compile-time checking of percpu area accesses.

   This has caused a small amount of fallout - two or three issues were
   reported. In all cases the calling code was found to be incorrect.

 - The series "Some cleanup for memcg" from Chen Ridong implements some
   relatively monir cleanups for the memcontrol code.

 - The series "mm: fixes for device-exclusive entries (hmm)" from David
   Hildenbrand fixes a boatload of issues which David found then using
   device-exclusive PTE entries when THP is enabled. More work is
   needed, but this makes thins better - our own HMM selftests now
   succeed.

 - The series "mm: zswap: remove z3fold and zbud" from Yosry Ahmed
   remove the z3fold and zbud implementations. They have been deprecated
   for half a year and nobody has complained.

 - The series "mm: further simplify VMA merge operation" from Lorenzo
   Stoakes implements numerous simplifications in this area. No runtime
   effects are anticipated.

 - The series "mm/madvise: remove redundant mmap_lock operations from
   process_madvise()" from SeongJae Park rationalizes the locking in the
   madvise() implementation. Performance gains of 20-25% were observed
   in one MADV_DONTNEED microbenchmark.

 - The series "Tiny cleanup and improvements about SWAP code" from
   Baoquan He contains a number of touchups to issues which Baoquan
   noticed when working on the swap code.

 - The series "mm: kmemleak: Usability improvements" from Catalin
   Marinas implements a couple of improvements to the kmemleak
   user-visible output.

 - The series "mm/damon/paddr: fix large folios access and schemes
   handling" from Usama Arif provides a couple of fixes for DAMON's
   handling of large folios.

 - The series "mm/damon/core: fix wrong and/or useless damos_walk()
   behaviors" from SeongJae Park fixes a few issues with the accuracy of
   kdamond's walking of DAMON regions.

 - The series "expose mapping wrprotect, fix fb_defio use" from Lorenzo
   Stoakes changes the interaction between framebuffer deferred-io and
   core MM. No functional changes are anticipated - this is preparatory
   work for the future removal of page structure fields.

 - The series "mm/damon: add support for hugepage_size DAMOS filter"
   from Usama Arif adds a DAMOS filter which permits the filtering by
   huge page sizes.

 - The series "mm: permit guard regions for file-backed/shmem mappings"
   from Lorenzo Stoakes extends the guard region feature from its
   present "anon mappings only" state. The feature now covers shmem and
   file-backed mappings.

 - The series "mm: batched unmap lazyfree large folios during
   reclamation" from Barry Song cleans up and speeds up the unmapping
   for pte-mapped large folios.

 - The series "reimplement per-vma lock as a refcount" from Suren
   Baghdasaryan puts the vm_lock back into the vma. Our reasons for
   pulling it out were largely bogus and that change made the code more
   messy. This patchset provides small (0-10%) improvements on one
   microbenchmark.

 - The series "Docs/mm/damon: misc DAMOS filters documentation fixes and
   improves" from SeongJae Park does some maintenance work on the DAMON
   docs.

 - The series "hugetlb/CMA improvements for large systems" from Frank
   van der Linden addresses a pile of issues which have been observed
   when using CMA on large machines.

 - The series "mm/damon: introduce DAMOS filter type for unmapped pages"
   from SeongJae Park enables users of DMAON/DAMOS to filter my the
   page's mapped/unmapped status.

 - The series "zsmalloc/zram: there be preemption" from Sergey
   Senozhatsky teaches zram to run its compression and decompression
   operations preemptibly.

 - The series "selftests/mm: Some cleanups from trying to run them" from
   Brendan Jackman fixes a pile of unrelated issues which Brendan
   encountered while runnimg our selftests.

 - The series "fs/proc/task_mmu: add guard region bit to pagemap" from
   Lorenzo Stoakes permits userspace to use /proc/pid/pagemap to
   determine whether a particular page is a guard page.

 - The series "mm, swap: remove swap slot cache" from Kairui Song
   removes the swap slot cache from the allocation path - it simply
   wasn't being effective.

 - The series "mm: cleanups for device-exclusive entries (hmm)" from
   David Hildenbrand implements a number of unrelated cleanups in this
   code.

 - The series "mm: Rework generic PTDUMP configs" from Anshuman Khandual
   implements a number of preparatoty cleanups to the GENERIC_PTDUMP
   Kconfig logic.

 - The series "mm/damon: auto-tune aggregation interval" from SeongJae
   Park implements a feedback-driven automatic tuning feature for
   DAMON's aggregation interval tuning.

 - The series "Fix lazy mmu mode" from Ryan Roberts fixes some issues in
   powerpc, sparc and x86 lazy MMU implementations. Ryan did this in
   preparation for implementing lazy mmu mode for arm64 to optimize
   vmalloc.

 - The series "mm/page_alloc: Some clarifications for migratetype
   fallback" from Brendan Jackman reworks some commentary to make the
   code easier to follow.

 - The series "page_counter cleanup and size reduction" from Shakeel
   Butt cleans up the page_counter code and fixes a size increase which
   we accidentally added late last year.

 - The series "Add a command line option that enables control of how
   many threads should be used to allocate huge pages" from Thomas
   Prescher does that. It allows the careful operator to significantly
   reduce boot time by tuning the parallalization of huge page
   initialization.

 - The series "Fix calculations in trace_balance_dirty_pages() for cgwb"
   from Tang Yizhou fixes the tracing output from the dirty page
   balancing code.

 - The series "mm/damon: make allow filters after reject filters useful
   and intuitive" from SeongJae Park improves the handling of allow and
   reject filters. Behaviour is made more consistent and the documention
   is updated accordingly.

 - The series "Switch zswap to object read/write APIs" from Yosry Ahmed
   updates zswap to the new object read/write APIs and thus permits the
   removal of some legacy code from zpool and zsmalloc.

 - The series "Some trivial cleanups for shmem" from Baolin Wang does as
   it claims.

 - The series "fs/dax: Fix ZONE_DEVICE page reference counts" from
   Alistair Popple regularizes the weird ZONE_DEVICE page refcount
   handling in DAX, permittig the removal of a number of special-case
   checks.

 - The series "refactor mremap and fix bug" from Lorenzo Stoakes is a
   preparatoty refactoring and cleanup of the mremap() code.

 - The series "mm: MM owner tracking for large folios (!hugetlb) +
   CONFIG_NO_PAGE_MAPCOUNT" from David Hildenbrand reworks the manner in
   which we determine whether a large folio is known to be mapped
   exclusively into a single MM.

 - The series "mm/damon: add sysfs dirs for managing DAMOS filters based
   on handling layers" from SeongJae Park adds a couple of new sysfs
   directories to ease the management of DAMON/DAMOS filters.

 - The series "arch, mm: reduce code duplication in mem_init()" from
   Mike Rapoport consolidates many per-arch implementations of
   mem_init() into code generic code, where that is practical.

 - The series "mm/damon/sysfs: commit parameters online via
   damon_call()" from SeongJae Park continues the cleaning up of sysfs
   access to DAMON internal data.

 - The series "mm: page_ext: Introduce new iteration API" from Luiz
   Capitulino reworks the page_ext initialization to fix a boot-time
   crash which was observed with an unusual combination of compile and
   cmdline options.

 - The series "Buddy allocator like (or non-uniform) folio split" from
   Zi Yan reworks the code to split a folio into smaller folios. The
   main benefit is lessened memory consumption: fewer post-split folios
   are generated.

 - The series "Minimize xa_node allocation during xarry split" from Zi
   Yan reduces the number of xarray xa_nodes which are generated during
   an xarray split.

 - The series "drivers/base/memory: Two cleanups" from Gavin Shan
   performs some maintenance work on the drivers/base/memory code.

 - The series "Add tracepoints for lowmem reserves, watermarks and
   totalreserve_pages" from Martin Liu adds some more tracepoints to the
   page allocator code.

 - The series "mm/madvise: cleanup requests validations and
   classifications" from SeongJae Park cleans up some warts which
   SeongJae observed during his earlier madvise work.

 - The series "mm/hwpoison: Fix regressions in memory failure handling"
   from Shuai Xue addresses two quite serious regressions which Shuai
   has observed in the memory-failure implementation.

 - The series "mm: reliable huge page allocator" from Johannes Weiner
   makes huge page allocations cheaper and more reliable by reducing
   fragmentation.

 - The series "Minor memcg cleanups &amp; prep for memdescs" from Matthew
   Wilcox is preparatory work for the future implementation of memdescs.

 - The series "track memory used by balloon drivers" from Nico Pache
   introduces a way to track memory used by our various balloon drivers.

 - The series "mm/damon: introduce DAMOS filter type for active pages"
   from Nhat Pham permits users to filter for active/inactive pages,
   separately for file and anon pages.

 - The series "Adding Proactive Memory Reclaim Statistics" from Hao Jia
   separates the proactive reclaim statistics from the direct reclaim
   statistics.

 - The series "mm/vmscan: don't try to reclaim hwpoison folio" from
   Jinjiang Tu fixes our handling of hwpoisoned pages within the reclaim
   code.

* tag 'mm-stable-2025-03-30-16-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (431 commits)
  mm/page_alloc: remove unnecessary __maybe_unused in order_to_pindex()
  x86/mm: restore early initialization of high_memory for 32-bits
  mm/vmscan: don't try to reclaim hwpoison folio
  mm/hwpoison: introduce folio_contain_hwpoisoned_page() helper
  cgroup: docs: add pswpin and pswpout items in cgroup v2 doc
  mm: vmscan: split proactive reclaim statistics from direct reclaim statistics
  selftests/mm: speed up split_huge_page_test
  selftests/mm: uffd-unit-tests support for hugepages &gt; 2M
  docs/mm/damon/design: document active DAMOS filter type
  mm/damon: implement a new DAMOS filter type for active pages
  fs/dax: don't disassociate zero page entries
  MM documentation: add "Unaccepted" meminfo entry
  selftests/mm: add commentary about 9pfs bugs
  fork: use __vmalloc_node() for stack allocation
  docs/mm: Physical Memory: Populate the "Zones" section
  xen: balloon: update the NR_BALLOON_PAGES state
  hv_balloon: update the NR_BALLOON_PAGES state
  balloon_compaction: update the NR_BALLOON_PAGES state
  meminfo: add a per node counter for balloon drivers
  mm: remove references to folio in __memcg_kmem_uncharge_page()
  ...
</pre>
</div>
</content>
</entry>
<entry>
<title>fbcon: Use static attribute groups for sysfs entries</title>
<updated>2025-03-26T21:39:21+00:00</updated>
<author>
<name>Shixiong Ou</name>
<email>oushixiong@kylinos.cn</email>
</author>
<published>2025-03-14T06:09:41+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=26c36247a44098ccab3d16aa7d5329db87aa7236'/>
<id>26c36247a44098ccab3d16aa7d5329db87aa7236</id>
<content type='text'>
Using device_create_with_groups() to simplify creation and removal.
Same as commit 1083a7be4504 ("tty: Use static attribute groups for
sysfs entries").

Signed-off-by: Shixiong Ou &lt;oushixiong@kylinos.cn&gt;
Acked-by: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Using device_create_with_groups() to simplify creation and removal.
Same as commit 1083a7be4504 ("tty: Use static attribute groups for
sysfs entries").

Signed-off-by: Shixiong Ou &lt;oushixiong@kylinos.cn&gt;
Acked-by: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>fbdev: Refactoring the fbcon packed pixel drawing routines</title>
<updated>2025-03-26T21:39:21+00:00</updated>
<author>
<name>Zsolt Kajtar</name>
<email>soci@c64.rulez.org</email>
</author>
<published>2025-03-09T18:47:15+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=eabb0329308729a9073785705224b4efeed081de'/>
<id>eabb0329308729a9073785705224b4efeed081de</id>
<content type='text'>
The original version duplicated more or less the same algorithms for
both system and i/o memory.

In this version the drawing algorithms (copy/fill/blit) are separate
from the memory access (system and i/o). The two parts are getting
combined in the loadable module sources. This also makes it more robust
against wrong memory access type or alignment mistakes as there's no
direct pointer access or arithmetic in the algorithm sources anymore.

Due to liberal use of inlining the compiled result is a single function
in all 6 cases, without unnecessary function calls. Unlike earlier the
use of macros could be minimized as apparently both gcc and clang is
capable now to do the same with inline functions just as well.

What wasn't quite the same in the two variants is the support for pixel
order reversing. This version is capable to do that for both system and
I/O memory, and not only for the latter. As demand for low bits per
pixel modes isn't high there's a configuration option to enable this
separately for the CFB and SYS modules.

The pixel reversing algorithm is different than earlier and was designed
so that it can take advantage of bit order reversing instructions on
architectures which have them. And even for higher bits per pixel modes
like four bpp.

One of the shortcomings of the earlier version was the incomplete
support for foreign endian framebuffers. Now all three drawing
algorithms produce correct output on both endians with native and
foreign framebuffers. This is one of the important differences even if
otherwise the algorithms don't look too different than before.

All three routines work now with aligned native word accesses. As a
consequence blitting isn't limited to 32 bits on 64 bit architectures as
it was before.

The old routines silently assumed that rows are a multiple of the word
size. Due to how the new routines function this isn't a requirement any
more and access will be done aligned regardless. However if the
framebuffer is configured like that then some of the fast paths won't be
available.

As this code is supposed to be running on all supported architectures it
wasn't optimized for a particular one. That doesn't mean I haven't
looked at the disassembly. That's where I noticed that it isn't a good
idea to use the fallback bitreversing code for example.

The low bits per pixel modes should be faster than before as the new
routines can blit 4 pixels at a time.

On the higher bits per pixel modes I retained the specialized aligned
routines so it should be more or less the same, except on 64 bit
architectures. There the blitting word size is double now which means 32
BPP isn't done a single pixel a time now.

The code was tested on x86, amd64, mips32 and mips64. The latter two in
big endian configuration. Originally thought I can get away with the
first two, but with such bit twisting code byte ordering is tricky and
not really possible to get right without actually verifying it.

While writing such routines isn't rocket science a lot of time was spent
on making sure that pixel ordering, foreign byte order, various bits per
pixels, cpu endianness and word size will give the expected result in
all sorts of combinations without making it overly complicated or full
with special cases.

Signed-off-by: Zsolt Kajtar &lt;soci@c64.rulez.org&gt;
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The original version duplicated more or less the same algorithms for
both system and i/o memory.

In this version the drawing algorithms (copy/fill/blit) are separate
from the memory access (system and i/o). The two parts are getting
combined in the loadable module sources. This also makes it more robust
against wrong memory access type or alignment mistakes as there's no
direct pointer access or arithmetic in the algorithm sources anymore.

Due to liberal use of inlining the compiled result is a single function
in all 6 cases, without unnecessary function calls. Unlike earlier the
use of macros could be minimized as apparently both gcc and clang is
capable now to do the same with inline functions just as well.

What wasn't quite the same in the two variants is the support for pixel
order reversing. This version is capable to do that for both system and
I/O memory, and not only for the latter. As demand for low bits per
pixel modes isn't high there's a configuration option to enable this
separately for the CFB and SYS modules.

The pixel reversing algorithm is different than earlier and was designed
so that it can take advantage of bit order reversing instructions on
architectures which have them. And even for higher bits per pixel modes
like four bpp.

One of the shortcomings of the earlier version was the incomplete
support for foreign endian framebuffers. Now all three drawing
algorithms produce correct output on both endians with native and
foreign framebuffers. This is one of the important differences even if
otherwise the algorithms don't look too different than before.

All three routines work now with aligned native word accesses. As a
consequence blitting isn't limited to 32 bits on 64 bit architectures as
it was before.

The old routines silently assumed that rows are a multiple of the word
size. Due to how the new routines function this isn't a requirement any
more and access will be done aligned regardless. However if the
framebuffer is configured like that then some of the fast paths won't be
available.

As this code is supposed to be running on all supported architectures it
wasn't optimized for a particular one. That doesn't mean I haven't
looked at the disassembly. That's where I noticed that it isn't a good
idea to use the fallback bitreversing code for example.

The low bits per pixel modes should be faster than before as the new
routines can blit 4 pixels at a time.

On the higher bits per pixel modes I retained the specialized aligned
routines so it should be more or less the same, except on 64 bit
architectures. There the blitting word size is double now which means 32
BPP isn't done a single pixel a time now.

The code was tested on x86, amd64, mips32 and mips64. The latter two in
big endian configuration. Originally thought I can get away with the
first two, but with such bit twisting code byte ordering is tricky and
not really possible to get right without actually verifying it.

While writing such routines isn't rocket science a lot of time was spent
on making sure that pixel ordering, foreign byte order, various bits per
pixels, cpu endianness and word size will give the expected result in
all sorts of combinations without making it overly complicated or full
with special cases.

Signed-off-by: Zsolt Kajtar &lt;soci@c64.rulez.org&gt;
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>fbdev: Register sysfs groups through device_add_group</title>
<updated>2025-03-26T21:39:20+00:00</updated>
<author>
<name>Shixiong Ou</name>
<email>oushixiong@kylinos.cn</email>
</author>
<published>2025-02-20T09:59:35+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=5fc830d6aca18a27a83906c8c916d545a0235ed5'/>
<id>5fc830d6aca18a27a83906c8c916d545a0235ed5</id>
<content type='text'>
Use device_add_group() to simplify creation.

Signed-off-by: Shixiong Ou &lt;oushixiong@kylinos.cn&gt;
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Use device_add_group() to simplify creation.

Signed-off-by: Shixiong Ou &lt;oushixiong@kylinos.cn&gt;
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>fbcon: Use correct erase colour for clearing in fbcon</title>
<updated>2025-03-26T21:39:19+00:00</updated>
<author>
<name>Zsolt Kajtar</name>
<email>soci@c64.rulez.org</email>
</author>
<published>2025-02-02T20:33:46+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=892c788d73fe4a94337ed092cb998c49fa8ecaf4'/>
<id>892c788d73fe4a94337ed092cb998c49fa8ecaf4</id>
<content type='text'>
The erase colour calculation for fbcon clearing should use get_color instead
of attr_col_ec, like everything else. The latter is similar but is not correct.
For example it's missing the depth dependent remapping and doesn't care about
blanking.

The problem can be reproduced by setting up the background colour to grey
(vt.color=0x70) and having an fbcon console set to 2bpp (4 shades of gray).
Now the background attribute should be 1 (dark gray) on the console.

If the screen is scrolled when pressing enter in a shell prompt at the bottom
line then the new line is cleared using colour 7 instead of 1. That's not
something fillrect likes (at 2bbp it expect 0-3) so the result is interesting.

This patch switches to get_color with vc_video_erase_char to determine the
erase colour from attr_col_ec. That makes the latter function redundant as
no other users were left.

Use correct erase colour for clearing in fbcon

Signed-off-by: Zsolt Kajtar &lt;soci@c64.rulez.org&gt;
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
The erase colour calculation for fbcon clearing should use get_color instead
of attr_col_ec, like everything else. The latter is similar but is not correct.
For example it's missing the depth dependent remapping and doesn't care about
blanking.

The problem can be reproduced by setting up the background colour to grey
(vt.color=0x70) and having an fbcon console set to 2bpp (4 shades of gray).
Now the background attribute should be 1 (dark gray) on the console.

If the screen is scrolled when pressing enter in a shell prompt at the bottom
line then the new line is cleared using colour 7 instead of 1. That's not
something fillrect likes (at 2bbp it expect 0-3) so the result is interesting.

This patch switches to get_color with vc_video_erase_char to determine the
erase colour from attr_col_ec. That makes the latter function redundant as
no other users were left.

Use correct erase colour for clearing in fbcon

Signed-off-by: Zsolt Kajtar &lt;soci@c64.rulez.org&gt;
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>fbdev: core: tileblit: Implement missing margin clearing for tileblit</title>
<updated>2025-03-26T21:39:19+00:00</updated>
<author>
<name>Zsolt Kajtar</name>
<email>soci@c64.rulez.org</email>
</author>
<published>2025-02-01T08:18:09+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=76d3ca89981354e1f85a3e0ad9ac4217d351cc72'/>
<id>76d3ca89981354e1f85a3e0ad9ac4217d351cc72</id>
<content type='text'>
I was wondering why there's garbage at the bottom of the screen when
tile blitting is used with an odd mode like 1080, 600 or 200. Sure there's
only space for half a tile but the same area is clean when the buffer
is bitmap.

Then later I found that it's supposed to be cleaned but that's not
implemented. So I took what's in bitblit and adapted it for tileblit.

This implementation was tested for both the horizontal and vertical case,
and now does the same as what's done for bitmap buffers.

If anyone is interested to reproduce the problem then I could bet that'd
be on a S3 or Ark. Just set up a mode with an odd line count and make
sure that the virtual size covers the complete tile at the bottom. E.g.
for 600 lines that's 608 virtual lines for a 16 tall tile. Then the
bottom area should be cleaned.

For the right side it's more difficult as there the drivers won't let an
odd size happen, unless the code is modified. But once it reports back a
few pixel columns short then fbcon won't use the last column. With the
patch that column is now clean.

Btw. the virtual size should be rounded up by the driver for both axes
(not only the horizontal) so that it's dividable by the tile size.
That's a driver bug but correcting it is not in scope for this patch.

Implement missing margin clearing for tileblit

Signed-off-by: Zsolt Kajtar &lt;soci@c64.rulez.org&gt;
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
I was wondering why there's garbage at the bottom of the screen when
tile blitting is used with an odd mode like 1080, 600 or 200. Sure there's
only space for half a tile but the same area is clean when the buffer
is bitmap.

Then later I found that it's supposed to be cleaned but that's not
implemented. So I took what's in bitblit and adapted it for tileblit.

This implementation was tested for both the horizontal and vertical case,
and now does the same as what's done for bitmap buffers.

If anyone is interested to reproduce the problem then I could bet that'd
be on a S3 or Ark. Just set up a mode with an odd line count and make
sure that the virtual size covers the complete tile at the bottom. E.g.
for 600 lines that's 608 virtual lines for a 16 tall tile. Then the
bottom area should be cleaned.

For the right side it's more difficult as there the drivers won't let an
odd size happen, unless the code is modified. But once it reports back a
few pixel columns short then fbcon won't use the last column. With the
patch that column is now clean.

Btw. the virtual size should be rounded up by the driver for both axes
(not only the horizontal) so that it's dividable by the tile size.
That's a driver bug but correcting it is not in scope for this patch.

Implement missing margin clearing for tileblit

Signed-off-by: Zsolt Kajtar &lt;soci@c64.rulez.org&gt;
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>fb_defio: do not use deprecated page-&gt;mapping, index fields</title>
<updated>2025-03-17T05:06:11+00:00</updated>
<author>
<name>Lorenzo Stoakes</name>
<email>lorenzo.stoakes@oracle.com</email>
</author>
<published>2025-02-08T15:52:56+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=6cdef2ddce2b7de8faca69061a6780080cfecc10'/>
<id>6cdef2ddce2b7de8faca69061a6780080cfecc10</id>
<content type='text'>
With the introduction of mapping_wrprotect_range() there is no need to use
folio_mkclean() in order to write-protect mappings of frame buffer pages,
and therefore no need to inappropriately set kernel-allocated page-&gt;index,
mapping fields to permit this operation.

Instead, store the pointer to the page cache object for the mapped driver
in the fb_deferred_io object, and use the already stored page offset from
the pageref object to look up mappings in order to write-protect them.

This is justified, as for the page objects to store a mapping pointer at
the point of assignment of pages, they must all reference the same
underlying address_space object.  Since the life time of the pagerefs is
also the lifetime of the fb_deferred_io object, storing the pointer here
makes sense.

This eliminates the need for all of the logic around setting and
maintaining page-&gt;index,mapping which we remove.

This eliminates the use of folio_mkclean() entirely but otherwise should
have no functional change.

[lorenzo.stoakes@oracle.com: fixup unused variable warnings]
  Link: https://lkml.kernel.org/r/d4018405-2762-4385-a816-e54cc23839ac@lucifer.local
Link: https://lkml.kernel.org/r/81171ab16c14e3df28f6de9d14982cee528d8519.1739029358.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Tested-by: Kajtar Zsolt &lt;soci@c64.rulez.org&gt;
Acked-by: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Cc: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: Jaya Kumar &lt;jayakumar.lkml@gmail.com&gt;
Cc: Maíra Canal &lt;mcanal@igalia.com&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Cc: Simona Vetter &lt;simona.vetter@ffwll.ch&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
With the introduction of mapping_wrprotect_range() there is no need to use
folio_mkclean() in order to write-protect mappings of frame buffer pages,
and therefore no need to inappropriately set kernel-allocated page-&gt;index,
mapping fields to permit this operation.

Instead, store the pointer to the page cache object for the mapped driver
in the fb_deferred_io object, and use the already stored page offset from
the pageref object to look up mappings in order to write-protect them.

This is justified, as for the page objects to store a mapping pointer at
the point of assignment of pages, they must all reference the same
underlying address_space object.  Since the life time of the pagerefs is
also the lifetime of the fb_deferred_io object, storing the pointer here
makes sense.

This eliminates the need for all of the logic around setting and
maintaining page-&gt;index,mapping which we remove.

This eliminates the use of folio_mkclean() entirely but otherwise should
have no functional change.

[lorenzo.stoakes@oracle.com: fixup unused variable warnings]
  Link: https://lkml.kernel.org/r/d4018405-2762-4385-a816-e54cc23839ac@lucifer.local
Link: https://lkml.kernel.org/r/81171ab16c14e3df28f6de9d14982cee528d8519.1739029358.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Tested-by: Kajtar Zsolt &lt;soci@c64.rulez.org&gt;
Acked-by: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Cc: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Helge Deller &lt;deller@gmx.de&gt;
Cc: Jaya Kumar &lt;jayakumar.lkml@gmail.com&gt;
Cc: Maíra Canal &lt;mcanal@igalia.com&gt;
Cc: Matthew Wilcox &lt;willy@infradead.org&gt;
Cc: Simona Vetter &lt;simona.vetter@ffwll.ch&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>fbdev: Fix recursive dependencies wrt BACKLIGHT_CLASS_DEVICE</title>
<updated>2024-12-17T17:06:10+00:00</updated>
<author>
<name>Thomas Zimmermann</name>
<email>tzimmermann@suse.de</email>
</author>
<published>2024-12-16T07:42:47+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=8fc38062be3f692ff8816da84fde71972530bcc4'/>
<id>8fc38062be3f692ff8816da84fde71972530bcc4</id>
<content type='text'>
Do not select BACKLIGHT_CLASS_DEVICE from FB_BACKLIGHT. The latter
only controls backlight support within fbdev core code and data
structures.

Make fbdev drivers depend on BACKLIGHT_CLASS_DEVICE and let users
select it explicitly. Fixes warnings about recursive dependencies,
such as

error: recursive dependency detected!
	symbol BACKLIGHT_CLASS_DEVICE is selected by FB_BACKLIGHT
	symbol FB_BACKLIGHT is selected by FB_SH_MOBILE_LCDC
	symbol FB_SH_MOBILE_LCDC depends on FB_DEVICE
	symbol FB_DEVICE depends on FB_CORE
	symbol FB_CORE is selected by DRM_GEM_DMA_HELPER
	symbol DRM_GEM_DMA_HELPER is selected by DRM_PANEL_ILITEK_ILI9341
	symbol DRM_PANEL_ILITEK_ILI9341 depends on BACKLIGHT_CLASS_DEVICE

BACKLIGHT_CLASS_DEVICE is user-selectable, so making drivers adapt to
it is the correct approach in any case. For most drivers, backlight
support is also configurable separately.

v3:
- Select BACKLIGHT_CLASS_DEVICE in PowerMac defconfigs (Christophe)
- Fix PMAC_BACKLIGHT module dependency corner cases (Christophe)
v2:
- s/BACKLIGHT_DEVICE_CLASS/BACKLIGHT_CLASS_DEVICE (Helge)
- Fix fbdev driver-dependency corner case (Arnd)

Signed-off-by: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Reviewed-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20241216074450.8590-2-tzimmermann@suse.de
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Do not select BACKLIGHT_CLASS_DEVICE from FB_BACKLIGHT. The latter
only controls backlight support within fbdev core code and data
structures.

Make fbdev drivers depend on BACKLIGHT_CLASS_DEVICE and let users
select it explicitly. Fixes warnings about recursive dependencies,
such as

error: recursive dependency detected!
	symbol BACKLIGHT_CLASS_DEVICE is selected by FB_BACKLIGHT
	symbol FB_BACKLIGHT is selected by FB_SH_MOBILE_LCDC
	symbol FB_SH_MOBILE_LCDC depends on FB_DEVICE
	symbol FB_DEVICE depends on FB_CORE
	symbol FB_CORE is selected by DRM_GEM_DMA_HELPER
	symbol DRM_GEM_DMA_HELPER is selected by DRM_PANEL_ILITEK_ILI9341
	symbol DRM_PANEL_ILITEK_ILI9341 depends on BACKLIGHT_CLASS_DEVICE

BACKLIGHT_CLASS_DEVICE is user-selectable, so making drivers adapt to
it is the correct approach in any case. For most drivers, backlight
support is also configurable separately.

v3:
- Select BACKLIGHT_CLASS_DEVICE in PowerMac defconfigs (Christophe)
- Fix PMAC_BACKLIGHT module dependency corner cases (Christophe)
v2:
- s/BACKLIGHT_DEVICE_CLASS/BACKLIGHT_CLASS_DEVICE (Helge)
- Fix fbdev driver-dependency corner case (Arnd)

Signed-off-by: Thomas Zimmermann &lt;tzimmermann@suse.de&gt;
Reviewed-by: Arnd Bergmann &lt;arnd@arndb.de&gt;
Link: https://patchwork.freedesktop.org/patch/msgid/20241216074450.8590-2-tzimmermann@suse.de
</pre>
</div>
</content>
</entry>
<entry>
<title>fbcon: break earlier in search_fb_in_map and search_for_mapped_con</title>
<updated>2024-09-26T16:25:12+00:00</updated>
<author>
<name>Qianqiang Liu</name>
<email>qianqiang.liu@163.com</email>
</author>
<published>2024-09-26T11:59:11+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=2555906fd53e0a5239431d44fad695b420e94fdd'/>
<id>2555906fd53e0a5239431d44fad695b420e94fdd</id>
<content type='text'>
Break the for loop immediately upon finding the target, making the
process more efficient.

Signed-off-by: Qianqiang Liu &lt;qianqiang.liu@163.com&gt;
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
Break the for loop immediately upon finding the target, making the
process more efficient.

Signed-off-by: Qianqiang Liu &lt;qianqiang.liu@163.com&gt;
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</pre>
</div>
</content>
</entry>
<entry>
<title>fbcon: Fix a NULL pointer dereference issue in fbcon_putcs</title>
<updated>2024-09-26T16:20:27+00:00</updated>
<author>
<name>Qianqiang Liu</name>
<email>qianqiang.liu@163.com</email>
</author>
<published>2024-09-25T05:29:36+00:00</published>
<link rel='alternate' type='text/html' href='https://git.tavy.me/linux-stable.git/commit/?id=5b97eebcce1b4f3f07a71f635d6aa3af96c236e7'/>
<id>5b97eebcce1b4f3f07a71f635d6aa3af96c236e7</id>
<content type='text'>
syzbot has found a NULL pointer dereference bug in fbcon.
Here is the simplified C reproducer:

struct param {
	uint8_t type;
	struct tiocl_selection ts;
};

int main()
{
	struct fb_con2fbmap con2fb;
	struct param param;

	int fd = open("/dev/fb1", 0, 0);

	con2fb.console = 0x19;
	con2fb.framebuffer = 0;
	ioctl(fd, FBIOPUT_CON2FBMAP, &amp;con2fb);

	param.type = 2;
	param.ts.xs = 0; param.ts.ys = 0;
	param.ts.xe = 0; param.ts.ye = 0;
	param.ts.sel_mode = 0;

	int fd1 = open("/dev/tty1", O_RDWR, 0);
	ioctl(fd1, TIOCLINUX, &amp;param);

	con2fb.console = 1;
	con2fb.framebuffer = 0;
	ioctl(fd, FBIOPUT_CON2FBMAP, &amp;con2fb);

	return 0;
}

After calling ioctl(fd1, TIOCLINUX, &amp;param), the subsequent ioctl(fd, FBIOPUT_CON2FBMAP, &amp;con2fb)
causes the kernel to follow a different execution path:

 set_con2fb_map
  -&gt; con2fb_init_display
   -&gt; fbcon_set_disp
    -&gt; redraw_screen
     -&gt; hide_cursor
      -&gt; clear_selection
       -&gt; highlight
        -&gt; invert_screen
         -&gt; do_update_region
          -&gt; fbcon_putcs
           -&gt; ops-&gt;putcs

Since ops-&gt;putcs is a NULL pointer, this leads to a kernel panic.
To prevent this, we need to call set_blitting_type() within set_con2fb_map()
to properly initialize ops-&gt;putcs.

Reported-by: syzbot+3d613ae53c031502687a@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=3d613ae53c031502687a
Tested-by: syzbot+3d613ae53c031502687a@syzkaller.appspotmail.com
Signed-off-by: Qianqiang Liu &lt;qianqiang.liu@163.com&gt;
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</content>
<content type='xhtml'>
<div xmlns='http://www.w3.org/1999/xhtml'>
<pre>
syzbot has found a NULL pointer dereference bug in fbcon.
Here is the simplified C reproducer:

struct param {
	uint8_t type;
	struct tiocl_selection ts;
};

int main()
{
	struct fb_con2fbmap con2fb;
	struct param param;

	int fd = open("/dev/fb1", 0, 0);

	con2fb.console = 0x19;
	con2fb.framebuffer = 0;
	ioctl(fd, FBIOPUT_CON2FBMAP, &amp;con2fb);

	param.type = 2;
	param.ts.xs = 0; param.ts.ys = 0;
	param.ts.xe = 0; param.ts.ye = 0;
	param.ts.sel_mode = 0;

	int fd1 = open("/dev/tty1", O_RDWR, 0);
	ioctl(fd1, TIOCLINUX, &amp;param);

	con2fb.console = 1;
	con2fb.framebuffer = 0;
	ioctl(fd, FBIOPUT_CON2FBMAP, &amp;con2fb);

	return 0;
}

After calling ioctl(fd1, TIOCLINUX, &amp;param), the subsequent ioctl(fd, FBIOPUT_CON2FBMAP, &amp;con2fb)
causes the kernel to follow a different execution path:

 set_con2fb_map
  -&gt; con2fb_init_display
   -&gt; fbcon_set_disp
    -&gt; redraw_screen
     -&gt; hide_cursor
      -&gt; clear_selection
       -&gt; highlight
        -&gt; invert_screen
         -&gt; do_update_region
          -&gt; fbcon_putcs
           -&gt; ops-&gt;putcs

Since ops-&gt;putcs is a NULL pointer, this leads to a kernel panic.
To prevent this, we need to call set_blitting_type() within set_con2fb_map()
to properly initialize ops-&gt;putcs.

Reported-by: syzbot+3d613ae53c031502687a@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=3d613ae53c031502687a
Tested-by: syzbot+3d613ae53c031502687a@syzkaller.appspotmail.com
Signed-off-by: Qianqiang Liu &lt;qianqiang.liu@163.com&gt;
Signed-off-by: Helge Deller &lt;deller@gmx.de&gt;
</pre>
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