linux-stable.git/Documentation/vm, branch v5.13

mm/slub: clarify verification reporting

2021-06-16T16:24:42+00:00

Patch series "Actually fix freelist pointer vs redzoning", v4.

This fixes redzoning vs the freelist pointer (both for middle-position
and very small caches).  Both are "theoretical" fixes, in that I see no
evidence of such small-sized caches actually be used in the kernel, but
that's no reason to let the bugs continue to exist, especially since
people doing local development keep tripping over it.  :)

This patch (of 3):

Instead of repeating "Redzone" and "Poison", clarify which sides of
those zones got tripped.  Additionally fix column alignment in the
trailer.

Before:

  BUG test (Tainted: G    B            ): Redzone overwritten
  ...
  Redzone (____ptrval____): bb bb bb bb bb bb bb bb      ........
  Object (____ptrval____): f6 f4 a5 40 1d e8            ...@..
  Redzone (____ptrval____): 1a aa                        ..
  Padding (____ptrval____): 00 00 00 00 00 00 00 00      ........

After:

  BUG test (Tainted: G    B            ): Right Redzone overwritten
  ...
  Redzone  (____ptrval____): bb bb bb bb bb bb bb bb      ........
  Object   (____ptrval____): f6 f4 a5 40 1d e8            ...@..
  Redzone  (____ptrval____): 1a aa                        ..
  Padding  (____ptrval____): 00 00 00 00 00 00 00 00      ........

The earlier commits that slowly resulted in the "Before" reporting were:

  d86bd1bece6f ("mm/slub: support left redzone")
  ffc79d288000 ("slub: use print_hex_dump")
  2492268472e7 ("SLUB: change error reporting format to follow lockdep loosely")

Link: https://lkml.kernel.org/r/20210608183955.280836-1-keescook@chromium.org
Link: https://lkml.kernel.org/r/20210608183955.280836-2-keescook@chromium.org
Link: https://lore.kernel.org/lkml/cfdb11d7-fb8e-e578-c939-f7f5fb69a6bd@suse.cz/
Signed-off-by: Kees Cook 
Acked-by: Vlastimil Babka 
Cc: Marco Elver 
Cc: "Lin, Zhenpeng" 
Cc: Christoph Lameter 
Cc: Pekka Enberg 
Cc: David Rientjes 
Cc: Joonsoo Kim 
Cc: Roman Gushchin 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: gup: remove FOLL_SPLIT

2021-04-30T18:20:37+00:00

Since commit 5a52c9df62b4 ("uprobe: use FOLL_SPLIT_PMD instead of
FOLL_SPLIT") and commit ba925fa35057 ("s390/gmap: improve THP splitting")
FOLL_SPLIT has not been used anymore.  Remove the dead code.

Link: https://lkml.kernel.org/r/20210330203900.9222-1-shy828301@gmail.com
Signed-off-by: Yang Shi 
Reviewed-by: John Hubbard 
Reviewed-by: Jason Gunthorpe 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/page_owner: record the timestamp of all pages during free

2021-04-30T18:20:36+00:00

Collect the time when each allocation is freed, to help with memory
analysis with kdump/ramdump.  Add the timestamp also in the page_owner
debugfs file and print it in dump_page().

Having another timestamp when we free the page helps for debugging page
migration issues.  For example both alloc and free timestamps being the
same can gave hints that there is an issue with migrating memory, as
opposed to a page just being dropped during migration.

Link: https://lkml.kernel.org/r/20210203175905.12267-1-georgi.djakov@linaro.org
Signed-off-by: Georgi Djakov 
Acked-by: Vlastimil Babka 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/debug_vm_pgtable/basic: add validation for dirtiness after write protect

2021-02-24T21:38:27+00:00

Patch series "mm/debug_vm_pgtable: Some minor updates", v3.

This series contains some cleanups and new test suggestions from Catalin
from an earlier discussion.

https://lore.kernel.org/linux-mm/20201123142237.GF17833@gaia/

This patch (of 2):

This adds validation tests for dirtiness after write protect conversion
for each page table level.  There are two new separate test types involved
here.

The first test ensures that a given page table entry does not become dirty
after pxx_wrprotect().  This is important for platforms like arm64 which
transfers and drops the hardware dirty bit (!PTE_RDONLY) to the software
dirty bit while making it an write protected one.  This test ensures that
no fresh page table entry could be created with hardware dirty bit set.
The second test ensures that a given page table entry always preserve the
dirty information across pxx_wrprotect().

This adds two previously missing PUD level basic tests and while here
fixes pxx_wrprotect() related typos in the documentation file.

Link: https://lkml.kernel.org/r/1611137241-26220-1-git-send-email-anshuman.khandual@arm.com
Link: https://lkml.kernel.org/r/1611137241-26220-2-git-send-email-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual 
Suggested-by: Catalin Marinas 
Tested-by: Gerald Schaefer  [s390]
Cc: Christophe Leroy 
Cc: Gerald Schaefer 
Cc: Vineet Gupta 
Cc: Paul Walmsley 
Cc: Steven Price 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation: fix typos in split page table lock description

2021-01-18T20:27:18+00:00

Signed-off-by: Rolf Eike Beer 
Link: https://lore.kernel.org/r/2338863.uUFqZTUbry@devpool47
Signed-off-by: Jonathan Corbet

mm/lru: revise the comments of lru_lock

2020-12-15T22:48:04+00:00

Since we changed the pgdat->lru_lock to lruvec->lru_lock, it's time to fix
the incorrect comments in code.  Also fixed some zone->lru_lock comment
error from ancient time.  etc.

I struggled to understand the comment above move_pages_to_lru() (surely
it never calls page_referenced()), and eventually realized that most of
it had got separated from shrink_active_list(): move that comment back.

Link: https://lkml.kernel.org/r/1604566549-62481-20-git-send-email-alex.shi@linux.alibaba.com
Signed-off-by: Hugh Dickins 
Signed-off-by: Alex Shi 
Acked-by: Johannes Weiner 
Acked-by: Vlastimil Babka 
Cc: Tejun Heo 
Cc: Andrey Ryabinin 
Cc: Jann Horn 
Cc: Mel Gorman 
Cc: Matthew Wilcox 
Cc: Alexander Duyck 
Cc: Andrea Arcangeli 
Cc: "Chen, Rong A" 
Cc: Daniel Jordan 
Cc: "Huang, Ying" 
Cc: Joonsoo Kim 
Cc: Kirill A. Shutemov 
Cc: Kirill A. Shutemov 
Cc: Konstantin Khlebnikov 
Cc: Michal Hocko 
Cc: Michal Hocko 
Cc: Mika Penttilä 
Cc: Minchan Kim 
Cc: Shakeel Butt 
Cc: Thomas Gleixner 
Cc: Vladimir Davydov 
Cc: Wei Yang 
Cc: Yang Shi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

arm: remove CONFIG_ARCH_HAS_HOLES_MEMORYMODEL

2020-12-15T20:13:42+00:00

ARM is the only architecture that defines CONFIG_ARCH_HAS_HOLES_MEMORYMODEL
which in turn enables memmap_valid_within() function that is intended to
verify existence  of struct page associated with a pfn when there are holes
in the memory map.

However, the ARCH_HAS_HOLES_MEMORYMODEL also enables HAVE_ARCH_PFN_VALID
and arch-specific pfn_valid() implementation that also deals with the holes
in the memory map.

The only two users of memmap_valid_within() call this function after
a call to pfn_valid() so the memmap_valid_within() check becomes redundant.

Remove CONFIG_ARCH_HAS_HOLES_MEMORYMODEL and memmap_valid_within() and rely
entirely on ARM's implementation of pfn_valid() that is now enabled
unconditionally.

Link: https://lkml.kernel.org/r/20201101170454.9567-9-rppt@kernel.org
Signed-off-by: Mike Rapoport 
Cc: Alexey Dobriyan 
Cc: Catalin Marinas 
Cc: Geert Uytterhoeven 
Cc: Greg Ungerer 
Cc: John Paul Adrian Glaubitz 
Cc: Jonathan Corbet 
Cc: Matt Turner 
Cc: Meelis Roos 
Cc: Michael Schmitz 
Cc: Russell King 
Cc: Tony Luck 
Cc: Vineet Gupta 
Cc: Will Deacon 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/page_owner: record timestamp and pid

2020-12-15T20:13:38+00:00

Collect the time for each allocation recorded in page owner so that
allocation "surges" can be measured.

Record the pid for each allocation recorded in page owner so that the
source of allocation "surges" can be better identified.

The above is very useful when doing memory analysis.  On a crash for
example, we can get this information from kdump (or ramdump) and parse it
to figure out memory allocation problems.

Please note that on x86_64 this increases the size of struct page_owner
from 16 bytes to 32.

Vlastimil: it's not a functionality intended for production, so unless
somebody says they need to enable page_owner for debugging and this
increase prevents them from fitting into available memory, let's not
complicate things with making this optional.

[lmark@codeaurora.org: v3]
  Link: https://lkml.kernel.org/r/20201210160357.27779-1-georgi.djakov@linaro.org

Link: https://lkml.kernel.org/r/20201209125153.10533-1-georgi.djakov@linaro.org
Signed-off-by: Liam Mark 
Signed-off-by: Georgi Djakov 
Acked-by: Vlastimil Babka 
Acked-by: Joonsoo Kim 
Cc: Jonathan Corbet 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'docs-5.10-2' of git://git.lwn.net/linux

2020-10-24T00:13:53+00:00

Pull documentation fixes from Jonathan Corbet:
 "A handful of late-arriving documentation fixes"

* tag 'docs-5.10-2' of git://git.lwn.net/linux:
  docs: Add two missing entries in vm sysctl index
  docs/vm: trivial fixes to several spelling mistakes
  docs: submitting-patches: describe preserving review/test tags
  Documentation: Chinese translation of Documentation/arm64/hugetlbpage.rst
  Documentation: x86: fix a missing word in x86_64/mm.rst.
  docs: driver-api: remove a duplicated index entry
  docs: lkdtm: Modernize and improve details
  docs: deprecated.rst: Expand str*cpy() replacement notes
  docs/cpu-load: format the example code.

docs/vm: trivial fixes to several spelling mistakes

2020-10-22T22:11:04+00:00

Fix several spelling mistakes in vm documentation.

Signed-off-by: Colin Ian King 
Link: https://lore.kernel.org/r/20201022142653.254429-1-colin.king@canonical.com
Signed-off-by: Jonathan Corbet