From: David Hildenbrand <[email protected]>
To: [email protected]
Cc: [email protected], [email protected],
[email protected], David Hildenbrand <[email protected]>,
Andrew Morton <[email protected]>,
Arnd Bergmann <[email protected]>,
Greg Kroah-Hartman <[email protected]>,
Nicolas Pitre <[email protected]>, Jens Axboe <[email protected]>,
Pavel Begunkov <[email protected]>
Subject: [PATCH mm-unstable v1 0/3] mm/nommu: don't use VM_MAYSHARE for MAP_PRIVATE mappings
Date: Mon, 2 Jan 2023 17:08:53 +0100 [thread overview]
Message-ID: <[email protected]> (raw)
Trying to reduce the confusion around VM_SHARED and VM_MAYSHARE first
requires !CONFIG_MMU to stop using VM_MAYSHARE for MAP_PRIVATE mappings.
CONFIG_MMU only sets VM_MAYSHARE for MAP_SHARED mappings.
This paves the way for further VM_MAYSHARE and VM_SHARED cleanups: for
example, renaming VM_MAYSHARED to VM_MAP_SHARED to make it cleaner what
is actually means.
Let's first get the weird case out of the way and not use VM_MAYSHARE in
MAP_PRIVATE mappings, using a new VM_MAYOVERLAY flag instead.
I am not a NOMMU expert, but my basic testing with risc64-nommu with
buildroot under QEMU revealed no surprises.
Cc: Andrew Morton <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Greg Kroah-Hartman <[email protected]>
Cc: Nicolas Pitre <[email protected]>
Cc: Jens Axboe <[email protected]>
Cc: Pavel Begunkov <[email protected]>
RFC -> v1:
* Rebased, retested
* "drivers/misc/open-dice: don't touch VM_MAYSHARE"
-> Added; as VM_MAYSHARE semantics are now clearer, it makes sense to
include this change in this series.
David Hildenbrand (3):
mm/nommu: factor out check for NOMMU shared mappings into
is_nommu_shared_mapping()
mm/nommu: don't use VM_MAYSHARE for MAP_PRIVATE mappings
drivers/misc/open-dice: don't touch VM_MAYSHARE
drivers/char/mem.c | 2 +-
drivers/misc/open-dice.c | 14 ++++-----
fs/cramfs/inode.c | 2 +-
fs/proc/task_nommu.c | 2 +-
fs/ramfs/file-nommu.c | 2 +-
fs/romfs/mmap-nommu.c | 2 +-
include/linux/mm.h | 20 +++++++++++++
io_uring/io_uring.c | 2 +-
mm/nommu.c | 62 +++++++++++++++++++++++-----------------
9 files changed, 68 insertions(+), 40 deletions(-)
--
2.39.0
next reply other threads:[~2023-01-02 16:10 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-01-02 16:08 David Hildenbrand [this message]
2023-01-02 16:08 ` [PATCH mm-unstable v1 1/3] mm/nommu: factor out check for NOMMU shared mappings into is_nommu_shared_mapping() David Hildenbrand
2023-01-02 16:08 ` [PATCH mm-unstable v1 2/3] mm/nommu: don't use VM_MAYSHARE for MAP_PRIVATE mappings David Hildenbrand
2023-01-02 16:08 ` [PATCH mm-unstable v1 3/3] drivers/misc/open-dice: don't touch VM_MAYSHARE David Hildenbrand
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