diff options
| author | Oscar Salvador <osalvador@suse.de> | 2025-06-30 16:42:11 +0200 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-07-13 16:38:22 -0700 |
| commit | cced784d2cb2a708cdfe4784514c2a10af3af37d (patch) | |
| tree | ecdc86ec9e089bd9b5add53f84e6bf6de42fb1e4 /mm/hugetlb.c | |
| parent | d531fd2ccf6b5ad95b718b5748e086f8d4aacf56 (diff) | |
| download | linux-cced784d2cb2a708cdfe4784514c2a10af3af37d.tar.gz | |
mm,hugetlb: drop obsolete comment about non-present pte and second faults
There is a comment in hugetlb_fault() that does not hold anymore. This
one:
/*
* vmf.orig_pte could be a migration/hwpoison vmf.orig_pte at this
* point, so this check prevents the kernel from going below assuming
* that we have an active hugepage in pagecache. This goto expects
* the 2nd page fault, and is_hugetlb_entry_(migration|hwpoisoned)
* check will properly handle it.
*/
This was written because back in the day we used to do:
hugetlb_fault () {
ptep = huge_pte_offset(...)
if (ptep) {
entry = huge_ptep_get(ptep)
if (unlikely(is_hugetlb_entry_migration(entry))
...
else if (unlikely(is_hugetlb_entry_hwpoisoned(entry)))
...
}
...
...
/*
* entry could be a migration/hwpoison entry at this point, so this
* check prevents the kernel from going below assuming that we have
* a active hugepage in pagecache. This goto expects the 2nd page fault,
* and is_hugetlb_entry_(migration|hwpoisoned) check will properly
* handle it.
*/
if (!pte_present(entry))
goto out_mutex;
...
}
The code was designed to check for hwpoisoned/migration entries upfront,
and then bail out if further down the pte was not present anymore, relying
on the second fault to properly handle migration/hwpoison entries that
time around.
The way we handle this is different nowadays, so drop the misleading
comment.
Link: https://lkml.kernel.org/r/20250627102904.107202-5-osalvador@suse.de
Link: https://lkml.kernel.org/r/20250630144212.156938-5-osalvador@suse.de
Signed-off-by: Oscar Salvador <osalvador@suse.de>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Gavin Guo <gavinguo@igalia.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/hugetlb.c')
| -rw-r--r-- | mm/hugetlb.c | 8 |
1 files changed, 1 insertions, 7 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 3e5cefd5e1d907..eead921831bf50 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -6727,13 +6727,7 @@ vm_fault_t hugetlb_fault(struct mm_struct *mm, struct vm_area_struct *vma, ret = 0; - /* - * vmf.orig_pte could be a migration/hwpoison vmf.orig_pte at this - * point, so this check prevents the kernel from going below assuming - * that we have an active hugepage in pagecache. This goto expects - * the 2nd page fault, and is_hugetlb_entry_(migration|hwpoisoned) - * check will properly handle it. - */ + /* Not present, either a migration or a hwpoisoned entry */ if (!pte_present(vmf.orig_pte)) { if (unlikely(is_hugetlb_entry_migration(vmf.orig_pte))) { /* |