Messages in this thread | | | From | David Hildenbrand <> | Subject | [PATCH mm-stable RFC 0/2] mm/nommu: don't use VM_MAYSHARE for MAP_PRIVATE mappings | Date | Mon, 19 Dec 2022 17:30:11 +0100 |
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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: Linus Torvalds <torvalds@linux-foundation.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Nicolas Pitre <nico@fluxnic.net> Cc: Jens Axboe <axboe@kernel.dk> Cc: Pavel Begunkov <asml.silence@gmail.com>
David Hildenbrand (2): 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/char/mem.c | 2 +- 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 +++++++++++++++++++++++++------------------ 8 files changed, 62 insertions(+), 32 deletions(-)
-- 2.38.1
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