On 2022/5/31 下午11:40, Jiaxun Yang wrote:
在 2022/5/31 5:36, Hongchen Zhang 写道:
pmd_mkinvalid should not clear dirty flag,otherwise the pmd
dirty flag,it's ok to just clear _PAGE_VALID.
Hi Hongcheng,
Sorry, what is meant by "otherwise the pmd dirty flag"? Could you please
elaborate?
In my humble opinion _PAGE_PRESENT must be cleared in mkinvalid as it
nolonger present here. And thus it lose the dirty status.
Thanks
- Jiaxun
Signed-off-by: Hongchen Zhang <zhanghongchen@xxxxxxxxxxx>
---
arch/mips/include/asm/pgtable.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/mips/include/asm/pgtable.h
b/arch/mips/include/asm/pgtable.h
index 374c632..d30a186 100644
--- a/arch/mips/include/asm/pgtable.h
+++ b/arch/mips/include/asm/pgtable.h
@@ -698,7 +698,7 @@ static inline pmd_t pmd_modify(pmd_t pmd, pgprot_t
newprot)
static inline pmd_t pmd_mkinvalid(pmd_t pmd)
{
- pmd_val(pmd) &= ~(_PAGE_PRESENT | _PAGE_VALID | _PAGE_DIRTY);
+ pmd_val(pmd) &= ~_PAGE_VALID;
return pmd;
}
Hi Jiaxun,
Refer to [ https://lkml.org/lkml/2018/10/17/231 ],Andrea said "
The clear of the real present bit during pmd (virtual) splitting is
done with pmdp_invalidate, that is created specifically to keeps
pmd_trans_huge=true, pmd_present=true despite the present bit is not
set. ". So it's wrong to clear _PAGE_PRESENT,because this will make
pmd_present=false.
On the other hand, There is no need to clear dirty flag too.
Thanks.
