From: Hugh Dickins <hughd@google.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Andi Kleen <ak@linux.intel.com>, Christoph Lameter <cl@linux.com>,
Matthew Wilcox <willy@infradead.org>,
Mike Kravetz <mike.kravetz@oracle.com>,
David Hildenbrand <david@redhat.com>,
Suren Baghdasaryan <surenb@google.com>,
Yang Shi <shy828301@gmail.com>,
Sidhartha Kumar <sidhartha.kumar@oracle.com>,
Vishal Moola <vishal.moola@gmail.com>,
Kefeng Wang <wangkefeng.wang@huawei.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Tejun Heo <tj@kernel.org>,
Mel Gorman <mgorman@techsingularity.net>,
Michal Hocko <mhocko@suse.com>,
"Huang, Ying" <ying.huang@intel.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: [PATCH v2 08/12] mempolicy: remove confusing MPOL_MF_LAZY dead code
Date: Tue, 3 Oct 2023 02:24:18 -0700 (PDT) [thread overview]
Message-ID: <80c9665c-1c3f-17ba-21a3-f6115cebf7d@google.com> (raw)
In-Reply-To: <ebc0987e-beff-8bfb-9283-234c2cbd17c5@google.com>
v3.8 commit b24f53a0bea3 ("mm: mempolicy: Add MPOL_MF_LAZY") introduced
MPOL_MF_LAZY, and included it in the MPOL_MF_VALID flags; but a720094ded8
("mm: mempolicy: Hide MPOL_NOOP and MPOL_MF_LAZY from userspace for now")
immediately removed it from MPOL_MF_VALID flags, pending further review.
"This will need to be revisited", but it has not been reinstated.
The present state is confusing: there is dead code in mm/mempolicy.c to
handle MPOL_MF_LAZY cases which can never occur. Remove that: it can be
resurrected later if necessary. But keep the definition of MPOL_MF_LAZY,
which must remain in the UAPI, even though it always fails with EINVAL.
https://lore.kernel.org/linux-mm/1553041659-46787-1-git-send-email-yang.shi@linux.alibaba.com/
links to a previous request to remove MPOL_MF_LAZY.
Signed-off-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
include/uapi/linux/mempolicy.h | 2 +-
mm/mempolicy.c | 18 ------------------
2 files changed, 1 insertion(+), 19 deletions(-)
diff --git a/include/uapi/linux/mempolicy.h b/include/uapi/linux/mempolicy.h
index 046d0ccba4cd..a8963f7ef4c2 100644
--- a/include/uapi/linux/mempolicy.h
+++ b/include/uapi/linux/mempolicy.h
@@ -48,7 +48,7 @@ enum {
#define MPOL_MF_MOVE (1<<1) /* Move pages owned by this process to conform
to policy */
#define MPOL_MF_MOVE_ALL (1<<2) /* Move every page to conform to policy */
-#define MPOL_MF_LAZY (1<<3) /* Modifies '_MOVE: lazy migrate on fault */
+#define MPOL_MF_LAZY (1<<3) /* UNSUPPORTED FLAG: Lazy migrate on fault */
#define MPOL_MF_INTERNAL (1<<4) /* Internal flags start here */
#define MPOL_MF_VALID (MPOL_MF_STRICT | \
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 5d99fd5cd60b..f3224a8b0f6c 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -636,12 +636,6 @@ unsigned long change_prot_numa(struct vm_area_struct *vma,
return nr_updated;
}
-#else
-static unsigned long change_prot_numa(struct vm_area_struct *vma,
- unsigned long addr, unsigned long end)
-{
- return 0;
-}
#endif /* CONFIG_NUMA_BALANCING */
static int queue_pages_test_walk(unsigned long start, unsigned long end,
@@ -680,14 +674,6 @@ static int queue_pages_test_walk(unsigned long start, unsigned long end,
if (endvma > end)
endvma = end;
- if (flags & MPOL_MF_LAZY) {
- /* Similar to task_numa_work, skip inaccessible VMAs */
- if (!is_vm_hugetlb_page(vma) && vma_is_accessible(vma) &&
- !(vma->vm_flags & VM_MIXEDMAP))
- change_prot_numa(vma, start, endvma);
- return 1;
- }
-
/*
* Check page nodes, and queue pages to move, in the current vma.
* But if no moving, and no strict checking, the scan can be skipped.
@@ -1274,9 +1260,6 @@ static long do_mbind(unsigned long start, unsigned long len,
if (IS_ERR(new))
return PTR_ERR(new);
- if (flags & MPOL_MF_LAZY)
- new->flags |= MPOL_F_MOF;
-
/*
* If we are using the default policy then operation
* on discontinuous address spaces is okay after all
@@ -1321,7 +1304,6 @@ static long do_mbind(unsigned long start, unsigned long len,
if (!err) {
if (!list_empty(&pagelist)) {
- WARN_ON_ONCE(flags & MPOL_MF_LAZY);
nr_failed |= migrate_pages(&pagelist, new_folio, NULL,
start, MIGRATE_SYNC, MR_MEMPOLICY_MBIND, NULL);
}
--
2.35.3
next prev parent reply other threads:[~2023-10-03 9:24 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-10-03 9:12 [PATCH v2 00/12] mempolicy: cleanups leading to NUMA mpol without vma Hugh Dickins
2023-10-03 9:15 ` [PATCH v2 01/12] hugetlbfs: drop shared NUMA mempolicy pretence Hugh Dickins
2023-10-03 9:16 ` [PATCH v2 02/12] kernfs: drop shared NUMA mempolicy hooks Hugh Dickins
2023-10-03 9:17 ` [PATCH v2 03/12] mempolicy: fix migrate_pages(2) syscall return nr_failed Hugh Dickins
2023-10-07 7:27 ` Huang, Ying
2023-10-03 9:19 ` [PATCH v2 04/12] mempolicy trivia: delete those ancient pr_debug()s Hugh Dickins
2023-10-03 9:20 ` [PATCH v2 05/12] mempolicy trivia: slightly more consistent naming Hugh Dickins
2023-10-03 9:21 ` [PATCH v2 06/12] mempolicy trivia: use pgoff_t in shared mempolicy tree Hugh Dickins
2023-10-03 9:22 ` [PATCH v2 07/12] mempolicy: mpol_shared_policy_init() without pseudo-vma Hugh Dickins
2023-10-03 9:24 ` Hugh Dickins [this message]
2023-10-03 22:28 ` [PATCH v2 08/12] mempolicy: remove confusing MPOL_MF_LAZY dead code Yang Shi
2023-10-03 9:25 ` [PATCH v2 09/12] mm: add page_rmappable_folio() wrapper Hugh Dickins
2023-10-03 9:26 ` [PATCH v2 10/12] mempolicy: alloc_pages_mpol() for NUMA policy without vma Hugh Dickins
2023-10-19 20:39 ` [PATCH v3 " Hugh Dickins
2023-10-23 16:53 ` domenico cerasuolo
2023-10-23 17:53 ` Andrew Morton
2023-10-23 18:10 ` domenico cerasuolo
2023-10-23 19:05 ` Johannes Weiner
2023-10-23 19:48 ` Hugh Dickins
2023-10-24 6:44 ` [PATCH] mempolicy: alloc_pages_mpol() for NUMA policy without vma: fix Hugh Dickins
2023-10-24 8:17 ` kernel test robot
2023-10-24 15:56 ` Hugh Dickins
2023-10-24 16:09 ` [PATCH v2] " Hugh Dickins
2023-10-23 18:34 ` [PATCH v3 10/12] mempolicy: alloc_pages_mpol() for NUMA policy without vma Zi Yan
2023-10-23 21:10 ` Hugh Dickins
2023-10-23 21:13 ` Zi Yan
2023-10-03 9:27 ` [PATCH v2 11/12] mempolicy: mmap_lock is not needed while migrating folios Hugh Dickins
2023-10-03 9:29 ` [PATCH v2 12/12] mempolicy: migration attempt to match interleave nodes Hugh Dickins
2023-10-24 6:50 ` [PATCH] mempolicy: migration attempt to match interleave nodes: fix Hugh Dickins
2023-10-24 15:18 ` Liam R. Howlett
2023-10-24 16:32 ` Hugh Dickins
2023-10-24 16:45 ` Matthew Wilcox
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