The patch titled
Subject: mm: handling Non-LRU pages returned by vm_normal_pages
has been added to the -mm mm-unstable branch. Its filename is
mm-handling-non-lru-pages-returned-by-vm_normal_pages.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-handling-non-lru-pages-returned-by-vm_normal_pages.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Alex Sierra <alex.sierra@xxxxxxx>
Subject: mm: handling Non-LRU pages returned by vm_normal_pages
Date: Fri, 15 Jul 2022 10:05:11 -0500
With DEVICE_COHERENT, we'll soon have vm_normal_pages() return
device-managed anonymous pages that are not LRU pages. Although they
behave like normal pages for purposes of mapping in CPU page, and for COW.
They do not support LRU lists, NUMA migration or THP.
Callers to follow_page() currently don't expect ZONE_DEVICE pages,
however, with DEVICE_COHERENT we might now return ZONE_DEVICE. Check for
ZONE_DEVICE pages in applicable users of follow_page() as well.
Link: https://lkml.kernel.org/r/20220715150521.18165-5-alex.sierra@xxxxxxx
Signed-off-by: Alex Sierra <alex.sierra@xxxxxxx>
Acked-by: Felix Kuehling <Felix.Kuehling@xxxxxxx> [v2]
Reviewed-by: Alistair Popple <apopple@xxxxxxxxxx> [v6]
Cc: Christoph Hellwig <hch@xxxxxx>
Cc: David Hildenbrand <david@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Jerome Glisse <jglisse@xxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Ralph Campbell <rcampbell@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 2 +-
mm/huge_memory.c | 2 +-
mm/khugepaged.c | 9 ++++++---
mm/ksm.c | 6 +++---
mm/madvise.c | 4 ++--
mm/memory.c | 10 +++++++++-
mm/mempolicy.c | 2 +-
mm/migrate.c | 4 ++--
mm/mlock.c | 2 +-
mm/mprotect.c | 2 +-
10 files changed, 27 insertions(+), 16 deletions(-)
--- a/fs/proc/task_mmu.c~mm-handling-non-lru-pages-returned-by-vm_normal_pages
+++ a/fs/proc/task_mmu.c
@@ -1803,7 +1803,7 @@ static struct page *can_gather_numa_stat
return NULL;
page = vm_normal_page(vma, addr, pte);
- if (!page)
+ if (!page || is_zone_device_page(page))
return NULL;
if (PageReserved(page))
--- a/mm/huge_memory.c~mm-handling-non-lru-pages-returned-by-vm_normal_pages
+++ a/mm/huge_memory.c
@@ -2910,7 +2910,7 @@ static int split_huge_pages_pid(int pid,
if (IS_ERR(page))
continue;
- if (!page)
+ if (!page || is_zone_device_page(page))
continue;
if (!is_transparent_hugepage(page))
--- a/mm/khugepaged.c~mm-handling-non-lru-pages-returned-by-vm_normal_pages
+++ a/mm/khugepaged.c
@@ -611,7 +611,7 @@ static int __collapse_huge_page_isolate(
goto out;
}
page = vm_normal_page(vma, address, pteval);
- if (unlikely(!page)) {
+ if (unlikely(!page) || unlikely(is_zone_device_page(page))) {
result = SCAN_PAGE_NULL;
goto out;
}
@@ -1261,7 +1261,7 @@ static int khugepaged_scan_pmd(struct mm
writable = true;
page = vm_normal_page(vma, _address, pteval);
- if (unlikely(!page)) {
+ if (unlikely(!page) || unlikely(is_zone_device_page(page))) {
result = SCAN_PAGE_NULL;
goto out_unmap;
}
@@ -1472,7 +1472,8 @@ void collapse_pte_mapped_thp(struct mm_s
goto abort;
page = vm_normal_page(vma, addr, *pte);
-
+ if (WARN_ON_ONCE(page && is_zone_device_page(page)))
+ page = NULL;
/*
* Note that uprobe, debugger, or MAP_PRIVATE may change the
* page table, but the new page will not be a subpage of hpage.
@@ -1490,6 +1491,8 @@ void collapse_pte_mapped_thp(struct mm_s
if (pte_none(*pte))
continue;
page = vm_normal_page(vma, addr, *pte);
+ if (WARN_ON_ONCE(page && is_zone_device_page(page)))
+ goto abort;
page_remove_rmap(page, vma, false);
}
--- a/mm/ksm.c~mm-handling-non-lru-pages-returned-by-vm_normal_pages
+++ a/mm/ksm.c
@@ -475,7 +475,7 @@ static int break_ksm(struct vm_area_stru
cond_resched();
page = follow_page(vma, addr,
FOLL_GET | FOLL_MIGRATION | FOLL_REMOTE);
- if (IS_ERR_OR_NULL(page))
+ if (IS_ERR_OR_NULL(page) || is_zone_device_page(page))
break;
if (PageKsm(page))
ret = handle_mm_fault(vma, addr,
@@ -560,7 +560,7 @@ static struct page *get_mergeable_page(s
goto out;
page = follow_page(vma, addr, FOLL_GET);
- if (IS_ERR_OR_NULL(page))
+ if (IS_ERR_OR_NULL(page) || is_zone_device_page(page))
goto out;
if (PageAnon(page)) {
flush_anon_page(vma, page, addr);
@@ -2311,7 +2311,7 @@ next_mm:
if (ksm_test_exit(mm))
break;
*page = follow_page(vma, ksm_scan.address, FOLL_GET);
- if (IS_ERR_OR_NULL(*page)) {
+ if (IS_ERR_OR_NULL(*page) || is_zone_device_page(*page)) {
ksm_scan.address += PAGE_SIZE;
cond_resched();
continue;
--- a/mm/madvise.c~mm-handling-non-lru-pages-returned-by-vm_normal_pages
+++ a/mm/madvise.c
@@ -421,7 +421,7 @@ regular_page:
continue;
page = vm_normal_page(vma, addr, ptent);
- if (!page)
+ if (!page || is_zone_device_page(page))
continue;
/*
@@ -639,7 +639,7 @@ static int madvise_free_pte_range(pmd_t
}
page = vm_normal_page(vma, addr, ptent);
- if (!page)
+ if (!page || is_zone_device_page(page))
continue;
/*
--- a/mm/memory.c~mm-handling-non-lru-pages-returned-by-vm_normal_pages
+++ a/mm/memory.c
@@ -633,6 +633,14 @@ struct page *vm_normal_page(struct vm_ar
if (is_zero_pfn(pfn))
return NULL;
if (pte_devmap(pte))
+ /*
+ * NOTE: New users of ZONE_DEVICE will not set pte_devmap()
+ * and will have refcounts incremented on their struct pages
+ * when they are inserted into PTEs, thus they are safe to
+ * return here. Legacy ZONE_DEVICE pages that set pte_devmap()
+ * do not have refcounts. Example of legacy ZONE_DEVICE is
+ * MEMORY_DEVICE_FS_DAX type in pmem or virtio_fs drivers.
+ */
return NULL;
print_bad_pte(vma, addr, pte, NULL);
@@ -4712,7 +4720,7 @@ static vm_fault_t do_numa_page(struct vm
pte = pte_modify(old_pte, vma->vm_page_prot);
page = vm_normal_page(vma, vmf->address, pte);
- if (!page)
+ if (!page || is_zone_device_page(page))
goto out_map;
/* TODO: handle PTE-mapped THP */
--- a/mm/mempolicy.c~mm-handling-non-lru-pages-returned-by-vm_normal_pages
+++ a/mm/mempolicy.c
@@ -524,7 +524,7 @@ static int queue_pages_pte_range(pmd_t *
if (!pte_present(*pte))
continue;
page = vm_normal_page(vma, addr, *pte);
- if (!page)
+ if (!page || is_zone_device_page(page))
continue;
/*
* vm_normal_page() filters out zero pages, but there might
--- a/mm/migrate.c~mm-handling-non-lru-pages-returned-by-vm_normal_pages
+++ a/mm/migrate.c
@@ -1630,7 +1630,7 @@ static int add_page_for_migration(struct
goto out;
err = -ENOENT;
- if (!page)
+ if (!page || is_zone_device_page(page))
goto out;
err = 0;
@@ -1821,7 +1821,7 @@ static void do_pages_stat_array(struct m
if (IS_ERR(page))
goto set_status;
- if (page) {
+ if (page && !is_zone_device_page(page)) {
err = page_to_nid(page);
put_page(page);
} else {
--- a/mm/mlock.c~mm-handling-non-lru-pages-returned-by-vm_normal_pages
+++ a/mm/mlock.c
@@ -333,7 +333,7 @@ static int mlock_pte_range(pmd_t *pmd, u
if (!pte_present(*pte))
continue;
page = vm_normal_page(vma, addr, *pte);
- if (!page)
+ if (!page || is_zone_device_page(page))
continue;
if (PageTransCompound(page))
continue;
--- a/mm/mprotect.c~mm-handling-non-lru-pages-returned-by-vm_normal_pages
+++ a/mm/mprotect.c
@@ -127,7 +127,7 @@ static unsigned long change_pte_range(st
continue;
page = vm_normal_page(vma, addr, oldpte);
- if (!page || PageKsm(page))
+ if (!page || is_zone_device_page(page) || PageKsm(page))
continue;
/* Also skip shared copy-on-write pages */
_
Patches currently in -mm which might be from alex.sierra@xxxxxxx are
mm-rename-is_pinnable_pages-to-is_longterm_pinnable_pages.patch
mm-move-page-zone-helpers-from-mmh-to-mmzoneh.patch
mm-add-zone-device-coherent-type-memory-support.patch
mm-handling-non-lru-pages-returned-by-vm_normal_pages.patch
mm-add-device-coherent-vma-selection-for-memory-migration.patch
drm-amdkfd-add-spm-support-for-svm.patch
lib-test_hmm-add-ioctl-to-get-zone-device-type.patch
lib-test_hmm-add-module-param-for-zone-device-type.patch
lib-add-support-for-device-coherent-type-in-test_hmm.patch
tools-update-hmm-test-to-support-device-coherent-type.patch
tools-update-test_hmm-script-to-support-sp-config.patch
tools-add-hmm-gup-tests-for-device-coherent-type.patch
tools-add-selftests-to-hmm-for-cow-in-device-memory.patch
