linux/include
Lorenzo Stoakes ab04b530e7 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>
2025-11-20 13:43:58 -08:00
..
acpi More power management updates for 6.18-rc1 2025-10-07 09:39:51 -07:00
asm-generic mm: actually mark kernel page table pages 2025-11-16 17:28:17 -08:00
clocksource
crypto This update includes the following changes: 2025-10-04 14:59:29 -07:00
cxl
drm kbuild: Let kernel-doc.py use PYTHON3 override 2025-11-08 19:42:22 -07:00
dt-bindings There's a bunch of patches here across drivers/clk/ to migrate drivers to use 2025-10-07 09:28:37 -07:00
hyperv hyperv: Remove the spurious null directive line 2025-10-02 21:21:24 +00:00
keys
kunit
kvm KVM: arm64: Kill leftovers of ad-hoc timer userspace access 2025-10-13 14:42:41 +01:00
linux mm: introduce copy-on-fork VMAs and make VM_MAYBE_GUARD one 2025-11-20 13:43:58 -08:00
math-emu
media
memory
misc
net memcg: net: track network throttling due to memcg memory pressure 2025-11-16 17:28:06 -08:00
pcmcia
ras mm: handle poisoning of pfn without struct pages 2025-11-16 17:28:29 -08:00
rdma
rv
scsi scsi: core: Fix the unit attention counter implementation 2025-10-21 21:09:36 -04:00
soc There's a bunch of patches here across drivers/clk/ to migrate drivers to use 2025-10-07 09:28:37 -07:00
sound ASoC: tas2781: Support more newly-released amplifiers tas58xx in the driver 2025-10-13 11:08:09 +01:00
target
trace mm: introduce VM_MAYBE_GUARD and make visible in /proc/$pid/smaps 2025-11-20 13:43:58 -08:00
uapi drm fixes for 6.18-rc5 2025-11-07 14:51:11 -08:00
ufs scsi: ufs: core: Add a quirk to suppress link_startup_again 2025-10-29 23:20:19 -04:00
vdso
video
xen
Kbuild