| f615cc92 | 22-Jan-2026 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
tools/testing/vma: add VMA userland tests for VMA flag functions
Now we have the capability to test the new helpers for the bitmap VMA
flags in userland, do so.
We also update the Makefile such tha
tools/testing/vma: add VMA userland tests for VMA flag functions
Now we have the capability to test the new helpers for the bitmap VMA
flags in userland, do so.
We also update the Makefile such that both VMA (and while we're here)
mm_struct flag sizes can be customised on build. We default to 128-bit to
enable testing of flags above word size even on 64-bit systems.
We add userland tests to ensure that we do not regress VMA flag behaviour
with the introduction when using bitmap VMA flags, nor accidentally
introduce unexpected results due to for instance higher bit values not
being correctly cleared/set.
As part of this change, make __mk_vma_flags() a custom function so we can
handle specifying invalid VMA bits. This is purposeful so we can have the
VMA tests work at lower and higher number of VMA flags without having to
duplicate code too much.
Link: https://lkml.kernel.org/r/7fe6afe9c8c61e4d3cfc9a2d50a5d24da8528e68.1769097829.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Damien Le Moal <dlemoal@kernel.org>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Yury Norov <ynorov@nvidia.com>
Cc: Chris Mason <clm@fb.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| a1f0daca | 22-Jan-2026 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
tools/testing/vma: separate out vma_internal.h into logical headers
The vma_internal.h file is becoming entirely unmanageable. It combines
duplicated kernel implementation logic that needs to be ke
tools/testing/vma: separate out vma_internal.h into logical headers
The vma_internal.h file is becoming entirely unmanageable. It combines
duplicated kernel implementation logic that needs to be kept in-sync with
the kernel, stubbed out declarations that we simply ignore for testing
purposes and custom logic added to aid testing.
If we separate each of the three things into separate headers it makes
things far more manageable, so do so:
* include/stubs.h contains the stubbed declarations,
* include/dup.h contains the duplicated kernel declarations, and
* include/custom.h contains declarations customised for testing.
[lorenzo.stoakes@oracle.com: avoid a duplicate struct define]
Link: https://lkml.kernel.org/r/1e032732-61c3-485c-9aa7-6a09016fefc1@lucifer.local
Link: https://lkml.kernel.org/r/dd57baf5b5986cb96a167150ac712cbe804b63ee.1769097829.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Damien Le Moal <dlemoal@kernel.org>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Yury Norov <ynorov@nvidia.com>
Cc: Chris Mason <clm@fb.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| 6aacab30 | 22-Jan-2026 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
tools/testing/vma: separate VMA userland tests into separate files
So far the userland VMA tests have been established as a rough expression
of what's been possible.
Adapt it into a more usable for
tools/testing/vma: separate VMA userland tests into separate files
So far the userland VMA tests have been established as a rough expression
of what's been possible.
Adapt it into a more usable form by separating out tests and shared
helper functions.
Since we test functions that are declared statically in mm/vma.c, we make
use of the trick of #include'ing kernel C files directly.
In order for the tests to continue to function, we must therefore also
this way into the tests/ directory.
We try to keep as much shared logic actually modularised into a separate
compilation unit in shared.c, however the merge_existing() and
attach_vma() helpers rely on statically declared mm/vma.c functions so
these must be declared in main.c.
Link: https://lkml.kernel.org/r/a0455ccfe4fdcd1c962c64f76304f612e5662a4e.1769097829.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Damien Le Moal <dlemoal@kernel.org>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Yury Norov <ynorov@nvidia.com>
Cc: Chris Mason <clm@fb.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| 53f1d936 | 22-Jan-2026 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
mm: make vm_area_desc utilise vma_flags_t only
Now we have eliminated all uses of vm_area_desc->vm_flags, eliminate this
field, and have mmap_prepare users utilise the vma_flags_t
vm_area_desc->vma_
mm: make vm_area_desc utilise vma_flags_t only
Now we have eliminated all uses of vm_area_desc->vm_flags, eliminate this
field, and have mmap_prepare users utilise the vma_flags_t
vm_area_desc->vma_flags field only.
As part of this change we alter is_shared_maywrite() to accept a
vma_flags_t parameter, and introduce is_shared_maywrite_vm_flags() for use
with legacy vm_flags_t flags.
We also update struct mmap_state to add a union between vma_flags and
vm_flags temporarily until the mmap logic is also converted to using
vma_flags_t.
Also update the VMA userland tests to reflect this change.
Link: https://lkml.kernel.org/r/fd2a2938b246b4505321954062b1caba7acfc77a.1769097829.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Damien Le Moal <dlemoal@kernel.org>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Yury Norov <ynorov@nvidia.com>
Cc: Chris Mason <clm@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| bae0ba7c | 22-Jan-2026 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
mm: add basic VMA flag operation helper functions
Now we have the mk_vma_flags() macro helper which permits easy
specification of any number of VMA flags, add helper functions which
operate with vma
mm: add basic VMA flag operation helper functions
Now we have the mk_vma_flags() macro helper which permits easy
specification of any number of VMA flags, add helper functions which
operate with vma_flags_t parameters.
This patch provides vma_flags_test[_mask](), vma_flags_set[_mask]() and
vma_flags_clear[_mask]() respectively testing, setting and clearing flags
with the _mask variants accepting vma_flag_t parameters, and the non-mask
variants implemented as macros which accept a list of flags.
This allows us to trivially test/set/clear aggregate VMA flag values as
necessary, for instance:
if (vma_flags_test(&flags, VMA_READ_BIT, VMA_WRITE_BIT))
goto readwrite;
vma_flags_set(&flags, VMA_READ_BIT, VMA_WRITE_BIT);
vma_flags_clear(&flags, VMA_READ_BIT, VMA_WRITE_BIT);
We also add a function for testing that ALL flags are set for convenience,
e.g.:
if (vma_flags_test_all(&flags, VMA_READ_BIT, VMA_MAYREAD_BIT)) {
/* Both READ and MAYREAD flags set */
...
}
The compiler generates optimal assembly for each such that they behave as
if the caller were setting the bitmap flags manually.
This is important for e.g. drivers which manipulate flag values rather
than a VMA's specific flag values.
We also add helpers for testing, setting and clearing flags for VMA's and
VMA descriptors to reduce boilerplate.
Also add the EMPTY_VMA_FLAGS define to aid initialisation of empty flags.
Finally, update the userland VMA tests to add the helpers there so they
can be utilised as part of userland testing.
Link: https://lkml.kernel.org/r/885d4897d67a6a57c0b07fa182a7055ad752df11.1769097829.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Damien Le Moal <dlemoal@kernel.org>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Yury Norov <ynorov@nvidia.com>
Cc: Chris Mason <clm@fb.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| a8700d42 | 21-Jan-2026 |
Liam R. Howlett <Liam.Howlett@oracle.com> |
mm: use unmap_desc struct for freeing page tables
Pass through the unmap_desc to free_pgtables() because it almost has
everything necessary and is already on the stack.
Updates testing code as nece
mm: use unmap_desc struct for freeing page tables
Pass through the unmap_desc to free_pgtables() because it almost has
everything necessary and is already on the stack.
Updates testing code as necessary.
No functional changes intended.
[Liam.Howlett@oracle.com: fix up unmap desc use on exit_mmap()]
Link: https://lkml.kernel.org/r/20260210214214.364856-1-Liam.Howlett@oracle.com
Link: https://lkml.kernel.org/r/20260121164946.2093480-12-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: SeongJae Park <sj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| 0df5a8d3 | 21-Jan-2026 |
Liam R. Howlett <Liam.Howlett@oracle.com> |
mm/vma: use unmap_desc in exit_mmap() and vms_clear_ptes()
Convert vms_clear_ptes() to use unmap_desc to call unmap_vmas() instead of
the large argument list. The UNMAP_STATE() cannot be used becau
mm/vma: use unmap_desc in exit_mmap() and vms_clear_ptes()
Convert vms_clear_ptes() to use unmap_desc to call unmap_vmas() instead of
the large argument list. The UNMAP_STATE() cannot be used because the vma
iterator in the vms does not point to the correct maple state
(mas_detach), and the tree_end will be set incorrectly. Setting up the
arguments manually avoids setting the struct up incorrectly and doing
extra work to get the correct pagetable range.
exit_mmap() also calls unmap_vmas() with many arguments. Using the
unmap_all_init() function to set the unmap descriptor for all vmas makes
this a bit easier to read.
Update to the vma test code is necessary to ensure testing continues to
function.
No functional changes intended.
Link: https://lkml.kernel.org/r/20260121164946.2093480-10-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: SeongJae Park <sj@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| d17f0241 | 18-Jan-2026 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
mm/rmap: separate out fork-only logic on anon_vma_clone()
Specify which operation is being performed to anon_vma_clone(), which
allows us to do checks specific to each operation type, as well as to
mm/rmap: separate out fork-only logic on anon_vma_clone()
Specify which operation is being performed to anon_vma_clone(), which
allows us to do checks specific to each operation type, as well as to
separate out and make clear that the anon_vma reuse logic is absolutely
specific to fork only.
This opens the door to further refactorings and refinements later as we
have more information to work with.
Link: https://lkml.kernel.org/r/cf7da7a2d973cdc72a1b80dd9a73260519e8fa9f.1768746221.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chris Li <chriscli@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Harry Yoo <harry.yoo@oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| 9ea35a25 | 25-Nov-2025 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
mm: introduce VMA flags bitmap type
It is useful to transition to using a bitmap for VMA flags so we can avoid
running out of flags, especially for 32-bit kernels which are constrained
to 32 flags,
mm: introduce VMA flags bitmap type
It is useful to transition to using a bitmap for VMA flags so we can avoid
running out of flags, especially for 32-bit kernels which are constrained
to 32 flags, necessitating some features to be limited to 64-bit kernels
only.
By doing so, we remove any constraint on the number of VMA flags moving
forwards no matter the platform and can decide in future to extend beyond
64 if required.
We start by declaring an opaque types, vma_flags_t (which resembles
mm_struct flags of type mm_flags_t), setting it to precisely the same size
as vm_flags_t, and place it in union with vm_flags in the VMA declaration.
We additionally update struct vm_area_desc equivalently placing the new
opaque type in union with vm_flags.
This change therefore does not impact the size of struct vm_area_struct or
struct vm_area_desc.
In order for the change to be iterative and to avoid impacting
performance, we designate VM_xxx declared bitmap flag values as those
which must exist in the first system word of the VMA flags bitmap.
We therefore declare vma_flags_clear_all(), vma_flags_overwrite_word(),
vma_flags_overwrite_word(), vma_flags_overwrite_word_once(),
vma_flags_set_word() and vma_flags_clear_word() in order to allow us to
update the existing vm_flags_*() functions to utilise these helpers.
This is a stepping stone towards converting users to the VMA flags bitmap
and behaves precisely as before.
By doing this, we can eliminate the existing private vma->__vm_flags field
in the vma->vm_flags union and replace it with the newly introduced opaque
type vma_flags, which we call flags so we refer to the new bitmap field as
vma->flags.
We update vma_flag_[test, set]_atomic() to account for the change also.
We adapt vm_flags_reset_once() to only clear those bits above the first
system word providing write-once semantics to the first system word (which
it is presumed the caller requires - and in all current use cases this is
so).
As we currently only specify that the VMA flags bitmap size is equal to
BITS_PER_LONG number of bits, this is a noop, but is defensive in
preparation for a future change that increases this.
We additionally update the VMA userland test declarations to implement the
same changes there.
Finally, we update the rust code to reference vma->vm_flags on update
rather than vma->__vm_flags which has been removed. This is safe for now,
albeit it is implicitly performing a const cast.
Once we introduce flag helpers we can improve this more.
No functional change intended.
Link: https://lkml.kernel.org/r/bab179d7b153ac12f221b7d65caac2759282cfe9.1764064557.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Acked-by: Alice Ryhl <aliceryhl@google.com> [rust]
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Wei Xu <weixugc@google.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| 4c613f51 | 25-Nov-2025 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
tools/testing/vma: eliminate dependency on vma->__vm_flags
The userland VMA test code relied on an internal implementation detail -
the existence of vma->__vm_flags to directly access VMA flags. Th
tools/testing/vma: eliminate dependency on vma->__vm_flags
The userland VMA test code relied on an internal implementation detail -
the existence of vma->__vm_flags to directly access VMA flags. There is
no need to do so when we have the vm_flags_*() helper functions available.
This is ugly, but also a subsequent commit will eliminate this field
altogether so this will shortly become broken.
This patch has us utilise the helper functions instead.
Link: https://lkml.kernel.org/r/6275c53a6bb20743edcbe92d3e130183b47d18d0.1764064557.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Pedro Falcato <pfalcato@suse.de>
Acked-by: Alice Ryhl <aliceryhl@google.com> [rust]
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Wei Xu <weixugc@google.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| 2b6a3f06 | 25-Nov-2025 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
mm: declare VMA flags by bit
Patch series "initial work on making VMA flags a bitmap", v3.
We are in the rather silly situation that we are running out of VMA flags
as they are currently limited to
mm: declare VMA flags by bit
Patch series "initial work on making VMA flags a bitmap", v3.
We are in the rather silly situation that we are running out of VMA flags
as they are currently limited to a system word in size.
This leads to absurd situations where we limit features to 64-bit
architectures only because we simply do not have the ability to add a flag
for 32-bit ones.
This is very constraining and leads to hacks or, in the worst case, simply
an inability to implement features we want for entirely arbitrary reasons.
This also of course gives us something of a Y2K type situation in mm where
we might eventually exhaust all of the VMA flags even on 64-bit systems.
This series lays the groundwork for getting away from this limitation by
establishing VMA flags as a bitmap whose size we can increase in future
beyond 64 bits if required.
This is necessarily a highly iterative process given the extensive use of
VMA flags throughout the kernel, so we start by performing basic steps.
Firstly, we declare VMA flags by bit number rather than by value,
retaining the VM_xxx fields but in terms of these newly introduced
VMA_xxx_BIT fields.
While we are here, we use sparse annotations to ensure that, when dealing
with VMA bit number parameters, we cannot be passed values which are not
declared as such - providing some useful type safety.
We then introduce an opaque VMA flag type, much like the opaque mm_struct
flag type introduced in commit bb6525f2f8c4 ("mm: add bitmap mm->flags
field"), which we establish in union with vma->vm_flags (but still set at
system word size meaning there is no functional or data type size change).
We update the vm_flags_xxx() helpers to use this new bitmap, introducing
sensible helpers to do so.
This series lays the foundation for further work to expand the use of
bitmap VMA flags and eventually eliminate these arbitrary restrictions.
This patch (of 4):
In order to lay the groundwork for VMA flags being a bitmap rather than a
system word in size, we need to be able to consistently refer to VMA flags
by bit number rather than value.
Take this opportunity to do so in an enum which we which is additionally
useful for tooling to extract metadata from.
This additionally makes it very clear which bits are being used for what
at a glance.
We use the VMA_ prefix for the bit values as it is logical to do so since
these reference VMAs. We consistently suffix with _BIT to make it clear
what the values refer to.
We declare bit values even when the flags that use them would not be
enabled by config options as this is simply clearer and clearly defines
what bit numbers are used for what, at no additional cost.
We declare a sparse-bitwise type vma_flag_t which ensures that users can't
pass around invalid VMA flags by accident and prepares for future work
towards VMA flags being a bitmap where we want to ensure bit values are
type safe.
To make life easier, we declare some macro helpers - DECLARE_VMA_BIT()
allows us to avoid duplication in the enum bit number declarations (and
maintaining the sparse __bitwise attribute), and INIT_VM_FLAG() is used to
assist with declaration of flags.
Unfortunately we can't declare both in the enum, as we run into issue with
logic in the kernel requiring that flags are preprocessor definitions, and
additionally we cannot have a macro which declares another macro so we
must define each flag macro directly.
Additionally, update the VMA userland testing vma_internal.h header to
include these changes.
We also have to fix the parameters to the vma_flag_*_atomic() functions
since VMA_MAYBE_GUARD_BIT is now of type vma_flag_t and sparse will
complain otherwise.
We have to update some rather silly if-deffery found in mm/task_mmu.c
which would otherwise break.
Finally, we update the rust binding helper as now it cannot auto-detect
the flags at all.
Link: https://lkml.kernel.org/r/cover.1764064556.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/3a35e5a0bcfa00e84af24cbafc0653e74deda64a.1764064556.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Acked-by: Alice Ryhl <aliceryhl@google.com> [rust]
Cc: Alex Gaynor <alex.gaynor@gmail.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andreas Hindborg <a.hindborg@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Ben Segall <bsegall@google.com>
Cc: Björn Roy Baron <bjorn3_gh@protonmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Cc: Chris Li <chrisl@kernel.org>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Dietmar Eggemann <dietmar.eggemann@arm.com>
Cc: Gary Guo <gary@garyguo.net>
Cc: Gregory Price <gourry@gourry.net>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Juri Lelli <juri.lelli@redhat.com>
Cc: Kairui Song <kasong@tencent.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mathew Brost <matthew.brost@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Miguel Ojeda <ojeda@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Trevor Gross <tmgross@umich.edu>
Cc: Valentin Schneider <vschneid@redhat.com>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
Cc: Wei Xu <weixugc@google.com>
Cc: xu xin <xu.xin16@zte.com.cn>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| 277a1ae3 | 13-Nov-2025 |
Chunyan Zhang <zhangchunyan@iscas.ac.cn> |
mm: softdirty: add pgtable_supports_soft_dirty()
Patch series "mm: Add soft-dirty and uffd-wp support for RISC-V", v15.
This patchset adds support for Svrsw60t59b [1] extension which is ratified
no
mm: softdirty: add pgtable_supports_soft_dirty()
Patch series "mm: Add soft-dirty and uffd-wp support for RISC-V", v15.
This patchset adds support for Svrsw60t59b [1] extension which is ratified
now, also add soft dirty and userfaultfd write protect tracking for
RISC-V.
The patches 1 and 2 add macros to allow architectures to define their own
checks if the soft-dirty / uffd_wp PTE bits are available, in other words
for RISC-V, the Svrsw60t59b extension is supported on which device the
kernel is running. Also patch1-2 are removing "ifdef
CONFIG_MEM_SOFT_DIRTY" "ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP" and "ifdef
CONFIG_PTE_MARKER_UFFD_WP" in favor of checks which if not overridden by
the architecture, no change in behavior is expected.
This patchset has been tested with kselftest mm suite in which soft-dirty,
madv_populate, test_unmerge_uffd_wp, and uffd-unit-tests run and pass, and
no regressions are observed in any of the other tests.
This patch (of 6):
Some platforms can customize the PTE PMD entry soft-dirty bit making it
unavailable even if the architecture provides the resource.
Add an API which architectures can define their specific implementations
to detect if soft-dirty bit is available on which device the kernel is
running.
This patch is removing "ifdef CONFIG_MEM_SOFT_DIRTY" in favor of
pgtable_supports_soft_dirty() checks that defaults to
IS_ENABLED(CONFIG_MEM_SOFT_DIRTY), if not overridden by the architecture,
no change in behavior is expected.
We make sure to never set VM_SOFTDIRTY if !pgtable_supports_soft_dirty(),
so we will never run into VM_SOFTDIRTY checks.
[lorenzo.stoakes@oracle.com: fix VMA selftests]
Link: https://lkml.kernel.org/r/dac6ddfe-773a-43d5-8f69-021b9ca4d24b@lucifer.local
Link: https://lkml.kernel.org/r/20251113072806.795029-1-zhangchunyan@iscas.ac.cn
Link: https://lkml.kernel.org/r/20251113072806.795029-2-zhangchunyan@iscas.ac.cn
Link: https://github.com/riscv-non-isa/riscv-iommu/pull/543 [1]
Signed-off-by: Chunyan Zhang <zhangchunyan@iscas.ac.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Conor Dooley <conor@kernel.org>
Cc: Deepak Gupta <debug@rivosinc.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andrew Jones <ajones@ventanamicro.com>
Cc: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| 6707915e | 17-Nov-2025 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
mm: propagate VM_SOFTDIRTY on merge
Patch series "make VM_SOFTDIRTY a sticky VMA flag", v2.
Currently we set VM_SOFTDIRTY when a new mapping is set up (whether by
establishing a new VMA, or via mer
mm: propagate VM_SOFTDIRTY on merge
Patch series "make VM_SOFTDIRTY a sticky VMA flag", v2.
Currently we set VM_SOFTDIRTY when a new mapping is set up (whether by
establishing a new VMA, or via merge) as implemented in __mmap_complete()
and do_brk_flags().
However, when performing a merge of existing mappings such as when
performing mprotect(), we may lose the VM_SOFTDIRTY flag.
Now we have the concept of making VMA flags 'sticky', that is that they
both don't prevent merge and, importantly, are propagated to merged VMAs,
this seems a sensible alternative to the existing special-casing of
VM_SOFTDIRTY.
We additionally add a self-test that demonstrates that this logic behaves
as expected.
This patch (of 2):
Currently we set VM_SOFTDIRTY when a new mapping is set up (whether by
establishing a new VMA, or via merge) as implemented in __mmap_complete()
and do_brk_flags().
However, when performing a merge of existing mappings such as when
performing mprotect(), we may lose the VM_SOFTDIRTY flag.
This is because currently we simply ignore VM_SOFTDIRTY for the purposes
of merge, so one VMA may possess the flag and another not, and whichever
happens to be the target VMA will be the one upon which the merge is
performed which may or may not have VM_SOFTDIRTY set.
Now we have the concept of 'sticky' VMA flags, let's make VM_SOFTDIRTY one
which solves this issue.
Additionally update VMA userland tests to propagate changes.
[akpm@linux-foundation.org: update comments, per Lorenzo]
Link: https://lkml.kernel.org/r/0019e0b8-ee1e-4359-b5ee-94225cbe5588@lucifer.local
Link: https://lkml.kernel.org/r/cover.1763399675.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/955478b5170715c895d1ef3b7f68e0cd77f76868.1763399675.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Acked-by: Andrey Vagin <avagin@gmail.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| 2197bb60 | 10-Nov-2025 |
Matthew Wilcox (Oracle) <willy@infradead.org> |
mm: add vma_start_write_killable()
Patch series "vma_start_write_killable"", v2.
When we added the VMA lock, we made a major oversight in not adding a
killable variant. That can run us into troubl
mm: add vma_start_write_killable()
Patch series "vma_start_write_killable"", v2.
When we added the VMA lock, we made a major oversight in not adding a
killable variant. That can run us into trouble where a thread takes the
VMA lock for read (eg handling a page fault) and then goes out to lunch
for an hour (eg doing reclaim). Another thread tries to modify the VMA,
taking the mmap_lock for write, then attempts to lock the VMA for write.
That blocks on the first thread, and ensures that every other page fault
now tries to take the mmap_lock for read. Because everything's in an
uninterruptible sleep, we can't kill the task, which makes me angry.
This patchset just adds vma_start_write_killable() and converts one caller
to use it. Most users are somewhat tricky to convert, so expect follow-up
individual patches per call-site which need careful analysis to make sure
we've done proper cleanup.
This patch (of 2):
The vma can be held read-locked for a substantial period of time, eg if
memory allocation needs to go into reclaim. It's useful to be able to
send fatal signals to threads which are waiting for the write lock.
Link: https://lkml.kernel.org/r/20251110203204.1454057-1-willy@infradead.org
Link: https://lkml.kernel.org/r/20251110203204.1454057-2-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Chris Li <chriscli@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| 29bef05e | 18-Nov-2025 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
tools/testing/vma: add VMA sticky userland tests
Modify existing merge new/existing userland VMA tests to assert that
sticky VMA flags behave as expected.
We do so by generating every possible perm
tools/testing/vma: add VMA sticky userland tests
Modify existing merge new/existing userland VMA tests to assert that
sticky VMA flags behave as expected.
We do so by generating every possible permutation of VMAs being
manipulated being sticky/not sticky and asserting that VMA flags with this
property retain are retained upon merge.
Link: https://lkml.kernel.org/r/5e2c7244485867befd052f8afc8188be6a4be670.1763460113.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| ab04b530 | 18-Nov-2025 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
mm: introduce copy-on-fork VMAs and make VM_MAYBE_GUARD one
Gather all the VMA flags whose presence implies that page tables must be
copied on fork into a single bitmap - VM_COPY_ON_FORK - and use t
mm: introduce copy-on-fork VMAs and make VM_MAYBE_GUARD one
Gather all the VMA flags whose presence implies that page tables must be
copied on fork into a single bitmap - VM_COPY_ON_FORK - and use this
rather than specifying individual flags in vma_needs_copy().
We also add VM_MAYBE_GUARD to this list, as it being set on a VMA implies
that there may be metadata contained in the page tables (that is - guard
markers) which would will not and cannot be propagated upon fork.
This was already being done manually previously in vma_needs_copy(), but
this makes it very explicit, alongside VM_PFNMAP, VM_MIXEDMAP and
VM_UFFD_WP all of which imply the same.
Note that VM_STICKY flags ought generally to be marked VM_COPY_ON_FORK too
- because equally a flag being VM_STICKY indicates that the VMA contains
metadat that is not propagated by being faulted in - i.e. that the VMA
metadata does not fully describe the VMA alone, and thus we must propagate
whatever metadata there is on a fork.
However, for maximum flexibility, we do not make this necessarily the case
here.
Link: https://lkml.kernel.org/r/5d41b24e7bc622cda0af92b6d558d7f4c0d1bc8c.1763460113.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| 64212ba0 | 18-Nov-2025 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
mm: implement sticky VMA flags
It is useful to be able to designate that certain flags are 'sticky', that
is, if two VMAs are merged one with a flag of this nature and one without,
the merged VMA se
mm: implement sticky VMA flags
It is useful to be able to designate that certain flags are 'sticky', that
is, if two VMAs are merged one with a flag of this nature and one without,
the merged VMA sets this flag.
As a result we ignore these flags for the purposes of determining VMA flag
differences between VMAs being considered for merge.
This patch therefore updates the VMA merge logic to perform this action,
with flags possessing this property being described in the VM_STICKY
bitmap.
Those flags which ought to be ignored for the purposes of VMA merge are
described in the VM_IGNORE_MERGE bitmap, which the VMA merge logic is also
updated to use.
As part of this change we place VM_SOFTDIRTY in VM_IGNORE_MERGE as it
already had this behaviour, alongside VM_STICKY as sticky flags by
implication must not disallow merge.
Ultimately it seems that we should make VM_SOFTDIRTY a sticky flag in its
own right, but this change is out of scope for this series.
The only sticky flag designated as such is VM_MAYBE_GUARD, so as a result
of this change, once the VMA flag is set upon guard region installation,
VMAs with guard ranges will now not have their merge behaviour impacted as
a result and can be freely merged with other VMAs without VM_MAYBE_GUARD
set.
Also update the comments for vma_modify_flags() to directly reference
sticky flags now we have established the concept.
We also update the VMA userland tests to account for the changes.
Link: https://lkml.kernel.org/r/22ad5269f7669d62afb42ce0c79bad70b994c58d.1763460113.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
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| 9119d6c2 | 18-Nov-2025 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
mm: update vma_modify_flags() to handle residual flags, document
The vma_modify_*() family of functions each either perform splits, a merge
or no changes at all in preparation for the requested modi
mm: update vma_modify_flags() to handle residual flags, document
The vma_modify_*() family of functions each either perform splits, a merge
or no changes at all in preparation for the requested modification to
occur.
When doing so for a VMA flags change, we currently don't account for any
flags which may remain (for instance, VM_SOFTDIRTY) despite the requested
change in the case that a merge succeeded.
This is made more important by subsequent patches which will introduce the
concept of sticky VMA flags which rely on this behaviour.
This patch fixes this by passing the VMA flags parameter as a pointer and
updating it accordingly on merge and updating callers to accommodate for
this.
Additionally, while we are here, we add kdocs for each of the
vma_modify_*() functions, as the fact that the requested modification is
not performed is confusing so it is useful to make this abundantly clear.
We also update the VMA userland tests to account for this change.
Link: https://lkml.kernel.org/r/23b5b549b0eaefb2922625626e58c2a352f3e93c.1763460113.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand (Red Hat) <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
|
| 5dba5cc2 | 18-Nov-2025 |
Lorenzo Stoakes <lorenzo.stoakes@oracle.com> |
mm: introduce VM_MAYBE_GUARD and make visible in /proc/$pid/smaps
Patch series "introduce VM_MAYBE_GUARD and make it sticky", v4.
Currently, guard regions are not visible to users except through
/p
mm: introduce VM_MAYBE_GUARD and make visible in /proc/$pid/smaps
Patch series "introduce VM_MAYBE_GUARD and make it sticky", v4.
Currently, guard regions are not visible to users except through
/proc/$pid/pagemap, with no explicit visibility at the VMA level.
This makes the feature less useful, as it isn't entirely apparent which
VMAs may have these entries present, especially when performing actions
which walk through memory regions such as those performed by CRIU.
This series addresses this issue by introducing the VM_MAYBE_GUARD flag
which fulfils this role, updating the smaps logic to display an entry for
these.
The semantics of this flag are that a guard region MAY be present if set
(we cannot be sure, as we can't efficiently track whether an
MADV_GUARD_REMOVE finally removes all the guard regions in a VMA) - but if
not set the VMA definitely does NOT have any guard regions present.
It's problematic to establish this flag without further action, because
that means that VMAs with guard regions in them become non-mergeable with
adjacent VMAs for no especially good reason.
To work around this, this series also introduces the concept of 'sticky'
VMA flags - that is flags which:
a. if set in one VMA and not in another still permit those VMAs to be
merged (if otherwise compatible).
b. When they are merged, the resultant VMA must have the flag set.
The VMA logic is updated to propagate these flags correctly.
Additionally, VM_MAYBE_GUARD being an explicit VMA flag allows us to solve
an issue with file-backed guard regions - previously these established an
anon_vma object for file-backed mappings solely to have vma_needs_copy()
correctly propagate guard region mappings to child processes.
We introduce a new flag alias VM_COPY_ON_FORK (which currently only
specifies VM_MAYBE_GUARD) and update vma_needs_copy() to check explicitly
for this flag and to copy page tables if it is present, which resolves
this issue.
Additionally, we add the ability for allow-listed VMA flags to be
atomically writable with only mmap/VMA read locks held.
The only flag we allow so far is VM_MAYBE_GUARD, which we carefully ensure
does not cause any races by being allowed to do so.
This allows us to maintain guard region installation as a read-locked
operation and not endure the overhead of obtaining a write lock here.
Finally we introduce extensive VMA userland tests to assert that the
sticky VMA logic behaves correctly as well as guard region self tests to
assert that smaps visibility is correctly implemented.
This patch (of 9):
Currently, if a user needs to determine if guard regions are present in a
range, they have to scan all VMAs (or have knowledge of which ones might
have guard regions).
Since commit 8e2f2aeb8b48 ("fs/proc/task_mmu: add guard region bit to
pagemap") and the related commit a516403787e0 ("fs/proc: extend the
PAGEMAP_SCAN ioctl to report guard regions"), users can use either
/proc/$pid/pagemap or the PAGEMAP_SCAN functionality to perform this
operation at a virtual address level.
This is not ideal, and it gives no visibility at a /proc/$pid/smaps level
that guard regions exist in ranges.
This patch remedies the situation by establishing a new VMA flag,
VM_MAYBE_GUARD, to indicate that a VMA may contain guard regions (it is
uncertain because we cannot reasonably determine whether a
MADV_GUARD_REMOVE call has removed all of the guard regions in a VMA, and
additionally VMAs may change across merge/split).
We utilise 0x800 for this flag which makes it available to 32-bit
architectures also, a flag that was previously used by VM_DENYWRITE, which
was removed in commit 8d0920bde5eb ("mm: remove VM_DENYWRITE") and hasn't
bee reused yet.
We also update the smaps logic and documentation to identify these VMAs.
Another major use of this functionality is that we can use it to identify
that we ought to copy page tables on fork.
We do not actually implement usage of this flag in mm/madvise.c yet as we
need to allow some VMA flags to be applied atomically under mmap/VMA read
lock in order to avoid the need to acquire a write lock for this purpose.
Link: https://lkml.kernel.org/r/cover.1763460113.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/cf8ef821eba29b6c5b5e138fffe95d6dcabdedb9.1763460113.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: David Hildenbrand (Red Hat) <david@kernel.org>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Cc: Andrei Vagin <avagin@gmail.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
show more ...
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