On 2/19/2024 7:48 PM, Wupeng Ma wrote:
From: Ma Wupeng <mawupeng1@xxxxxxxxxx>
This patch set is all about follow_phys() cleanups, so "Cleanup for PAT"
seems too generic.
Patch #1 move follow_phys to memtype.c since only pat use this.
Patch #2 cleanup parameter in follow_phys.
Patch #3 drop the unnecessary WARN_ON_ONCE if follow_phys fails.
I'm more curious why follow_phys() ended up this way?
follow_phys() was introduced in commit 28b2ee20c7cba ("access_process_vm
device memory infrastructure") in 2008 for getting a physical page address
for a virtual address, and used in generic_access_phys(). And later it's
used in x86 PAT code.
Commit 03668a4debf4f ("mm: use generic follow_pte() in follow_phys()") made
follow_phys() more of a wrapper of follow_pte(), and commit 96667f8a4382d
("mm: Close race in generic_access_phys") replaced follow_phys() with
follow_pte() in generic_access_phys(). And the end result is that
follow_phys() is used in x86 PAT code only.
As follow_phys() in untrack_pfn() can be replaced with follow_pfn(), then
maybe we don't have to keep follow_phys(), and just use follow_pte() in
track_pfn_copy()?
Thanks!
Xin
Changelog since v3:
- rebase to latest linux
- fix compile warnings
Changelog since v2:
- rebase to latest linux
Changelog since v1:
- split patch #1 into two patches based on Boris's advise
Ma Wupeng (3):
x86/mm/pat: Move follow_phys to pat-related file
x86/mm/pat: Cleanup unused parameter in follow_phys
x86/mm/pat: Remove WARN_ON_ONCE if follow_phys fails
arch/x86/mm/pat/memtype.c | 32 ++++++++++++++++++++++++++------
include/linux/mm.h | 2 --
mm/memory.c | 28 ----------------------------
3 files changed, 26 insertions(+), 36 deletions(-)
