On Tue, Jun 11, 2019 at 7:45 PM Catalin Marinas [off-list ref] wrote:

On Tue, Jun 11, 2019 at 05:35:31PM +0200, Andrey Konovalov wrote:

quoted

On Mon, Jun 10, 2019 at 4:28 PM Catalin Marinas [off-list ref] wrote:

quoted

On Mon, Jun 03, 2019 at 06:55:07PM +0200, Andrey Konovalov wrote:

quoted

This patch is a part of a series that extends arm64 kernel ABI to allow to
pass tagged user pointers (with the top byte set to something else other
than 0x00) as syscall arguments.

This patch allows tagged pointers to be passed to the following memory
syscalls: get_mempolicy, madvise, mbind, mincore, mlock, mlock2, mprotect,
mremap, msync, munlock.

Signed-off-by: Andrey Konovalov <redacted>

I would add in the commit log (and possibly in the code with a comment)
that mremap() and mmap() do not currently accept tagged hint addresses.
Architectures may interpret the hint tag as a background colour for the
corresponding vma. With this:

I'll change the commit log. Where do you you think I should put this
comment? Before mmap and mremap definitions in mm/?

On arm64 we use our own sys_mmap(). I'd say just add a comment on the
generic mremap() just before the untagged_addr() along the lines that
new_address is not untagged for preserving similar behaviour to mmap().

Will do in v17, thanks!

--
Catalin

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