Re: [PATCH v3 3/6] mm/huge_memory.c: rework the function do_huge_pmd_numa_page() slightly

[Zi Yan]

On 18 Mar 2021, at 8:27, Miaohe Lin wrote:

> The current code that checks if migrating misplaced transhuge page is
> needed is pretty hard to follow. Rework it and add a comment to make
> its logic more clear and improve readability.
>
> Signed-off-by: Miaohe Lin 
> ---
>  mm/huge_memory.c | 11 +--
>  1 file changed, 5 insertions(+), 6 deletions(-)
>
LGTM. Reviewed-by: Zi Yan 

—
Best Regards,
Yan Zi


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[PATCH v3 3/6] mm/huge_memory.c: rework the function do_huge_pmd_numa_page() slightly

[Miaohe Lin]

The current code that checks if migrating misplaced transhuge page is
needed is pretty hard to follow. Rework it and add a comment to make
its logic more clear and improve readability.

Signed-off-by: Miaohe Lin 
---
 mm/huge_memory.c | 11 +--
 1 file changed, 5 insertions(+), 6 deletions(-)

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 01b96c638e73..23964adf5db2 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1462,12 +1462,6 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, 
pmd_t pmd)
 */
page_locked = trylock_page(page);
target_nid = mpol_misplaced(page, vma, haddr);
-   if (target_nid == NUMA_NO_NODE) {
-   /* If the page was locked, there are no parallel migrations */
-   if (page_locked)
-   goto clear_pmdnuma;
-   }
-
/* Migration could have started since the pmd_trans_migrating check */
if (!page_locked) {
page_nid = NUMA_NO_NODE;
@@ -1476,6 +1470,11 @@ vm_fault_t do_huge_pmd_numa_page(struct vm_fault *vmf, 
pmd_t pmd)
spin_unlock(vmf->ptl);
put_and_wait_on_page_locked(page, TASK_UNINTERRUPTIBLE);
goto out;
+   } else if (target_nid == NUMA_NO_NODE) {
+   /* There are no parallel migrations and page is in the right
+* node. Clear the numa hinting info in this pmd.
+*/
+   goto clear_pmdnuma;
}
 
/*
-- 
2.19.1