mm/mprotect: minor can_change_pte_writable() cleanups

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We want to replicate this code for handling PMDs soon.

(1) No need to crash the kernel, warning and rejecting is good enough. As
    this will no longer get optimized out, drop the pte_write() check: no
    harm would be done.

(2) Add a comment why PROT_NONE mapped pages are excluded.

(3) Add a comment regarding MAP_SHARED handling and why we rely on the
    dirty bit in the PTE.

Link: https://lkml.kernel.org/r/20221108174652.198904-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

...

This commit is contained in:

David Hildenbrand 2022-11-08 18:46:47 +01:00 • committed by Andrew Morton

parent d84887739d

commit 7ea7e33384

1 changed files with 14 additions and 5 deletions

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mm/mprotect.c

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