linux.git/mm/vmalloc.c, branch v6.15

mm: vmalloc: only zero-init on vrealloc shrink

2025-05-25T07:53:48+00:00

The common case is to grow reallocations, and since init_on_alloc will
have already zeroed the whole allocation, we only need to zero when
shrinking the allocation.

Link: https://lkml.kernel.org/r/20250515214217.619685-2-kees@kernel.org
Fixes: a0309faf1cb0 ("mm: vmalloc: support more granular vrealloc() sizing")
Signed-off-by: Kees Cook 
Tested-by: Pawan Gupta 
Cc: Danilo Krummrich 
Cc: Eduard Zingerman 
Cc: "Erhard F." 
Cc: Shung-Hsi Yu 
Cc: "Uladzislau Rezki (Sony)" 
Cc: 
Signed-off-by: Andrew Morton

mm: vmalloc: actually use the in-place vrealloc region

2025-05-25T07:53:48+00:00

Patch series "mm: vmalloc: Actually use the in-place vrealloc region".

This fixes a performance regression[1] with vrealloc()[1].


The refactoring to not build a new vmalloc region only actually worked
when shrinking.  Actually return the resized area when it grows.  Ugh.

Link: https://lkml.kernel.org/r/20250515214217.619685-1-kees@kernel.org
Fixes: a0309faf1cb0 ("mm: vmalloc: support more granular vrealloc() sizing")
Signed-off-by: Kees Cook 
Reported-by: Shung-Hsi Yu 
Closes: https://lore.kernel.org/all/20250515-bpf-verifier-slowdown-vwo2meju4cgp2su5ckj@6gi6ssxbnfqg [1]
Tested-by: Eduard Zingerman 
Tested-by: Pawan Gupta 
Tested-by: Shung-Hsi Yu 
Reviewed-by: "Uladzislau Rezki (Sony)" 
Reviewed-by: Danilo Krummrich 
Cc: "Erhard F." 
Cc: 
Signed-off-by: Andrew Morton

mm: vmalloc: support more granular vrealloc() sizing

2025-05-08T06:39:41+00:00

Introduce struct vm_struct::requested_size so that the requested
(re)allocation size is retained separately from the allocated area size. 
This means that KASAN will correctly poison the correct spans of requested
bytes.  This also means we can support growing the usable portion of an
allocation that can already be supported by the existing area's existing
allocation.

Link: https://lkml.kernel.org/r/20250426001105.it.679-kees@kernel.org
Fixes: 3ddc2fefe6f3 ("mm: vmalloc: implement vrealloc()")
Signed-off-by: Kees Cook 
Reported-by: Erhard Furtner 
Closes: https://lore.kernel.org/all/20250408192503.6149a816@outsider.home/
Reviewed-by: Danilo Krummrich 
Cc: Michal Hocko 
Cc: "Uladzislau Rezki (Sony)" 
Cc: Vlastimil Babka 
Cc: 
Signed-off-by: Andrew Morton

mm/vmalloc: refactor __vmalloc_node_range_noprof()

2025-03-18T05:06:58+00:00

According to the code logic, the first parameter of the sub-function
__get_vm_area_node() should be size instead of real_size.

Then in __get_vm_area_node(), the size will be aligned, so the redundant
alignment operation is deleted.

The use of the real_size variable causes code redundancy, so it is removed
to simplify the code.

The real prefix is generally used to indicate the adjusted value of a
parameter, but according to the code logic, it should indicate the
original value, so it is recommended to rename it to original_align.

Link: https://lkml.kernel.org/r/20250306072131.800499-1-liuye@kylinos.cn
Signed-off-by: Liu Ye 
Reviewed-by: "Uladzislau Rezki (Sony)" 
Cc: Christop Hellwig 
Signed-off-by: Andrew Morton

mm: don't skip arch_sync_kernel_mappings() in error paths

2025-03-06T05:36:18+00:00

Fix callers that previously skipped calling arch_sync_kernel_mappings() if
an error occurred during a pgtable update.  The call is still required to
sync any pgtable updates that may have occurred prior to hitting the error
condition.

These are theoretical bugs discovered during code review.

Link: https://lkml.kernel.org/r/20250226121610.2401743-1-ryan.roberts@arm.com
Fixes: 2ba3e6947aed ("mm/vmalloc: track which page-table levels were modified")
Fixes: 0c95cba49255 ("mm: apply_to_pte_range warn and fail if a large pte is encountered")
Signed-off-by: Ryan Roberts 
Reviewed-by: Anshuman Khandual 
Reviewed-by: Catalin Marinas 
Cc: Christop Hellwig 
Cc: "Uladzislau Rezki (Sony)" 
Cc: 
Signed-off-by: Andrew Morton

mm: alloc_pages_bulk: rename API

2025-01-26T04:22:31+00:00

The previous commit removed the page_list argument from
alloc_pages_bulk_noprof() along with the alloc_pages_bulk_list() function.

Now that only the *_array() flavour of the API remains, we can do the
following renaming (along with the _noprof() ones):

  alloc_pages_bulk_array -> alloc_pages_bulk
  alloc_pages_bulk_array_mempolicy -> alloc_pages_bulk_mempolicy
  alloc_pages_bulk_array_node -> alloc_pages_bulk_node

Link: https://lkml.kernel.org/r/275a3bbc0be20fbe9002297d60045e67ab3d4ada.1734991165.git.luizcap@redhat.com
Signed-off-by: Luiz Capitulino 
Acked-by: David Hildenbrand 
Cc: Matthew Wilcox (Oracle) 
Cc: Mel Gorman 
Cc: Yunsheng Lin 
Signed-off-by: Andrew Morton

vmalloc: fix accounting with i915

2024-12-19T03:04:45+00:00

If the caller of vmap() specifies VM_MAP_PUT_PAGES (currently only the
i915 driver), we will decrement nr_vmalloc_pages and MEMCG_VMALLOC in
vfree().  These counters are incremented by vmalloc() but not by vmap() so
this will cause an underflow.  Check the VM_MAP_PUT_PAGES flag before
decrementing either counter.

Link: https://lkml.kernel.org/r/20241211202538.168311-1-willy@infradead.org
Fixes: b944afc9d64d ("mm: add a VM_MAP_PUT_PAGES flag for vmap")
Signed-off-by: Matthew Wilcox (Oracle) 
Acked-by: Johannes Weiner 
Reviewed-by: Shakeel Butt 
Reviewed-by: Balbir Singh 
Acked-by: Michal Hocko 
Cc: Christoph Hellwig 
Cc: Muchun Song 
Cc: Roman Gushchin 
Cc: "Uladzislau Rezki (Sony)" 
Cc: 
Signed-off-by: Andrew Morton

mm: fix vrealloc()'s KASAN poisoning logic

2024-12-06T03:54:44+00:00

When vrealloc() reuses already allocated vmap_area, we need to re-annotate
poisoned and unpoisoned portions of underlying memory according to the new
size.

This results in a KASAN splat recorded at [1].  A KASAN mis-reporting
issue where there is none.

Note, hard-coding KASAN_VMALLOC_PROT_NORMAL might not be exactly correct,
but KASAN flag logic is pretty involved and spread out throughout
__vmalloc_node_range_noprof(), so I'm using the bare minimum flag here and
leaving the rest to mm people to refactor this logic and reuse it here.

Link: https://lkml.kernel.org/r/20241126005206.3457974-1-andrii@kernel.org
Link: https://lore.kernel.org/bpf/67450f9b.050a0220.21d33d.0004.GAE@google.com/ [1]
Fixes: 3ddc2fefe6f3 ("mm: vmalloc: implement vrealloc()")
Signed-off-by: Andrii Nakryiko 
Cc: Alexei Starovoitov 
Cc: Christoph Hellwig 
Cc: Michal Hocko 
Cc: Uladzislau Rezki (Sony) 
Cc: Vlastimil Babka 
Cc: 
Signed-off-by: Andrew Morton

alloc_tag: populate memory for module tags as needed

2024-11-07T22:25:16+00:00

The memory reserved for module tags does not need to be backed by physical
pages until there are tags to store there.  Change the way we reserve this
memory to allocate only virtual area for the tags and populate it with
physical pages as needed when we load a module.

[surenb@google.com: avoid execmem_vmap() when !MMU]
  Link: https://lkml.kernel.org/r/20241031233611.3833002-1-surenb@google.com
Link: https://lkml.kernel.org/r/20241023170759.999909-5-surenb@google.com
Signed-off-by: Suren Baghdasaryan 
Reviewed-by: Pasha Tatashin 
Cc: Ard Biesheuvel 
Cc: Arnd Bergmann 
Cc: Borislav Petkov (AMD) 
Cc: Christoph Hellwig 
Cc: Daniel Gomez 
Cc: David Hildenbrand 
Cc: Davidlohr Bueso 
Cc: David Rientjes 
Cc: Dennis Zhou 
Cc: Johannes Weiner 
Cc: John Hubbard 
Cc: Jonathan Corbet 
Cc: Joonsoo Kim 
Cc: Kalesh Singh 
Cc: Kees Cook 
Cc: Kent Overstreet 
Cc: Liam R. Howlett 
Cc: Luis Chamberlain 
Cc: Matthew Wilcox 
Cc: Michal Hocko 
Cc: Mike Rapoport (Microsoft) 
Cc: Minchan Kim 
Cc: Paul E. McKenney 
Cc: Petr Pavlu 
Cc: Roman Gushchin 
Cc: Sami Tolvanen 
Cc: Sourav Panda 
Cc: Steven Rostedt (Google) 
Cc: Thomas Gleixner 
Cc: Thomas Huth 
Cc: Uladzislau Rezki (Sony) 
Cc: Vlastimil Babka 
Cc: Xiongwei Song 
Cc: Yu Zhao 
Signed-off-by: Andrew Morton

execmem: add support for cache of large ROX pages

2024-11-07T22:25:16+00:00

Using large pages to map text areas reduces iTLB pressure and improves
performance.

Extend execmem_alloc() with an ability to use huge pages with ROX
permissions as a cache for smaller allocations.

To populate the cache, a writable large page is allocated from vmalloc
with VM_ALLOW_HUGE_VMAP, filled with invalid instructions and then
remapped as ROX.

The direct map alias of that large page is exculded from the direct map.

Portions of that large page are handed out to execmem_alloc() callers
without any changes to the permissions.

When the memory is freed with execmem_free() it is invalidated again so
that it won't contain stale instructions.

An architecture has to implement execmem_fill_trapping_insns() callback
and select ARCH_HAS_EXECMEM_ROX configuration option to be able to use the
ROX cache.

The cache is enabled on per-range basis when an architecture sets
EXECMEM_ROX_CACHE flag in definition of an execmem_range.

Link: https://lkml.kernel.org/r/20241023162711.2579610-8-rppt@kernel.org
Signed-off-by: Mike Rapoport (Microsoft) 
Reviewed-by: Luis Chamberlain 
Tested-by: kdevops 
Cc: Andreas Larsson 
Cc: Andy Lutomirski 
Cc: Ard Biesheuvel 
Cc: Arnd Bergmann 
Cc: Borislav Petkov (AMD) 
Cc: Brian Cain 
Cc: Catalin Marinas 
Cc: Christophe Leroy 
Cc: Christoph Hellwig 
Cc: Dave Hansen 
Cc: Dinh Nguyen 
Cc: Geert Uytterhoeven 
Cc: Guo Ren 
Cc: Helge Deller 
Cc: Huacai Chen 
Cc: Ingo Molnar 
Cc: Johannes Berg 
Cc: John Paul Adrian Glaubitz 
Cc: Kent Overstreet 
Cc: Liam R. Howlett 
Cc: Mark Rutland 
Cc: Masami Hiramatsu (Google) 
Cc: Matt Turner 
Cc: Max Filippov 
Cc: Michael Ellerman 
Cc: Michal Simek 
Cc: Oleg Nesterov 
Cc: Palmer Dabbelt 
Cc: Peter Zijlstra 
Cc: Richard Weinberger 
Cc: Russell King 
Cc: Song Liu 
Cc: Stafford Horne 
Cc: Steven Rostedt (Google) 
Cc: Suren Baghdasaryan 
Cc: Thomas Bogendoerfer 
Cc: Thomas Gleixner 
Cc: Uladzislau Rezki (Sony) 
Cc: Vineet Gupta 
Cc: Will Deacon 
Signed-off-by: Andrew Morton