OpenCloudOS-Kernel/arch/parisc/mm
John David Anglin 67c35a3b64 parisc: Disable debug code regarding cache flushes in handle_nadtlb_fault()
Change the "BUG" to "WARNING" and disable the message because it triggers
occasionally in spite of the check in flush_cache_page_if_present.

The pte value extracted for the "from" page in copy_user_highpage is racy and
occasionally the pte is cleared before the flush is complete.  I assume that
the page is simultaneously flushed by flush_cache_mm before the pte is cleared
as nullifying the fdc doesn't seem to cause problems.

I investigated various locking scenarios but I wasn't able to find a way to
sequence the flushes.  This code is called for every COW break and locks impact
performance.

This patch is related to the bigger cache flush patch because we need the pte
on PA8800/PA8900 to flush using the vma context.
I have also seen this from copy_to_user_page and copy_from_user_page.

The messages appear infrequently when enabled.

Signed-off-by: John David Anglin <dave.anglin@bell.net>
Signed-off-by: Helge Deller <deller@gmx.de>
2022-05-17 21:49:06 +02:00
..
Makefile treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
fault.c parisc: Disable debug code regarding cache flushes in handle_nadtlb_fault() 2022-05-17 21:49:06 +02:00
fixmap.c parisc: Fix set_fixmap() on PA1.x CPUs 2021-11-01 12:00:22 +01:00
hugetlbpage.c hugetlb: pass vma into huge_pte_alloc() and huge_pmd_share() 2021-05-05 11:27:20 -07:00
init.c parisc: Drop __init from map_pages declaration 2022-01-28 10:15:33 +01:00
ioremap.c mm: remove unneeded includes of <asm/pgalloc.h> 2020-08-07 11:33:26 -07:00