The method of establishing mmap mapping for memory allocated by dmabuf
through vm_insert_page causes changes in the way dmabuf memory is
accounted for, primarily in the following three aspects:
(1) The memory usage of dmabuf is accounted for in mm->rss.
(2) /proc/self/smaps will account for the memory usage of dmabuf.
(3) Memory usage of dmabuf after mmap will be counted in Mapped in
/proc/meminfo.
By adding a VM_DMABUF_DIO_MAP flag, we address the memory accounting
issues in the three aspects mentioned above, ensuring that the memory
allocated by dmabuf with direct_io support does not undergo changes in
its memory accounting method.
Signed-off-by: Lei Liu <liulei.rjpt@xxxxxxxx>
---
drivers/dma-buf/heaps/system_heap.c | 2 ++
fs/proc/task_mmu.c | 8 +++++++-
include/linux/mm.h | 1 +
mm/memory.c | 15 ++++++++++-----
mm/rmap.c | 9 +++++----
5 files changed, 25 insertions(+), 10 deletions(-)
diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
index 87547791f9e1..1d6f08b1dc5b 100644
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -200,6 +200,8 @@ static int system_heap_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma)
struct sg_page_iter piter;
int ret;
+ vm_flags_set(vma, VM_DMABUF_DIO);
+
for_each_sgtable_page(table, &piter, vma->vm_pgoff) {
struct page *page = sg_page_iter_page(&piter);
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 71e5039d940d..8070fdd4ac7b 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -784,7 +784,13 @@ static void smap_gather_stats(struct vm_area_struct *vma,
/* Invalid start */
if (start >= vma->vm_end)
return;
-
+ /*
+ * The memory of DMABUF needs to be mmaped using vm_insert_page in order to
+ * support direct_io. It will not with VM_PFNMAP flag, but it does have the
+ * VM_DMABUF_DIO flag memory will be counted in the process's RSS.
+ */
+ if (vma->vm_flags & VM_DMABUF_DIO)
+ return;
if (vma->vm_file && shmem_mapping(vma->vm_file->f_mapping)) {
/*
* For shared or readonly shmem mappings we know that all
diff --git a/include/linux/mm.h b/include/linux/mm.h
index eb7c96d24ac0..86d23f1a9717 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -283,6 +283,7 @@ extern unsigned int kobjsize(const void *objp);
#define VM_UFFD_MISSING 0
#endif /* CONFIG_MMU */
#define VM_PFNMAP 0x00000400 /* Page-ranges managed without "struct page", just pure PFN */
+#define VM_DMABUF_DIO 0x00000800 /* Memory accounting for dmabuf support direct_io */
#define VM_UFFD_WP 0x00001000 /* wrprotect pages tracking */
#define VM_LOCKED 0x00002000
diff --git a/mm/memory.c b/mm/memory.c
index d10e616d7389..8b126ce0f788 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1003,7 +1003,8 @@ copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma
VM_WARN_ON_FOLIO(PageAnonExclusive(page), folio);
} else {
folio_dup_file_rmap_ptes(folio, page, nr);
- rss[mm_counter_file(folio)] += nr;
+ if (likely(!(src_vma->vm_flags & VM_DMABUF_DIO)))
+ rss[mm_counter_file(folio)] += nr;
}
if (any_writable)
pte = pte_mkwrite(pte, src_vma);
@@ -1031,7 +1032,8 @@ copy_present_ptes(struct vm_area_struct *dst_vma, struct vm_area_struct *src_vma
VM_WARN_ON_FOLIO(PageAnonExclusive(page), folio);
} else {
folio_dup_file_rmap_pte(folio, page);
- rss[mm_counter_file(folio)]++;
+ if (likely(!(src_vma->vm_flags & VM_DMABUF_DIO)))
+ rss[mm_counter_file(folio)]++;
}
copy_pte:
@@ -1488,7 +1490,8 @@ static __always_inline void zap_present_folio_ptes(struct mmu_gather *tlb,
}
if (pte_young(ptent) && likely(vma_has_recency(vma)))
folio_mark_accessed(folio);
- rss[mm_counter(folio)] -= nr;
+ if (likely(!(vma->vm_flags & VM_DMABUF_DIO)))
+ rss[mm_counter(folio)] -= nr;
} else {
/* We don't need up-to-date accessed/dirty bits. */
clear_full_ptes(mm, addr, pte, nr, tlb->fullmm);
@@ -1997,7 +2000,8 @@ static int insert_page_into_pte_locked(struct vm_area_struct *vma, pte_t *pte,
return -EBUSY;
/* Ok, finally just insert the thing.. */
folio_get(folio);
- inc_mm_counter(vma->vm_mm, mm_counter_file(folio));
+ if (likely(!(vma->vm_flags & VM_DMABUF_DIO)))
+ inc_mm_counter(vma->vm_mm, mm_counter_file(folio));
folio_add_file_rmap_pte(folio, page, vma);
set_pte_at(vma->vm_mm, addr, pte, mk_pte(page, prot));
return 0;
@@ -4641,7 +4645,8 @@ vm_fault_t do_set_pmd(struct vm_fault *vmf, struct page *page)
if (write)
entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma);
- add_mm_counter(vma->vm_mm, mm_counter_file(folio), HPAGE_PMD_NR);
+ if (likely(!(vma->vm_flags & VM_DMABUF_DIO)))
+ add_mm_counter(vma->vm_mm, mm_counter_file(folio), HPAGE_PMD_NR);
folio_add_file_rmap_pmd(folio, page, vma);
/*
diff --git a/mm/rmap.c b/mm/rmap.c
index e8fc5ecb59b2..17cab358acc1 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -1441,10 +1441,10 @@ static __always_inline void __folio_add_file_rmap(struct folio *folio,
VM_WARN_ON_FOLIO(folio_test_anon(folio), folio);
nr = __folio_add_rmap(folio, page, nr_pages, level, &nr_pmdmapped);
- if (nr_pmdmapped)
+ if (nr_pmdmapped && !(vma->vm_flags & VM_DMABUF_DIO))
__mod_node_page_state(pgdat, folio_test_swapbacked(folio) ?
NR_SHMEM_PMDMAPPED : NR_FILE_PMDMAPPED, nr_pmdmapped);
- if (nr)
+ if (nr && !(vma->vm_flags & VM_DMABUF_DIO))
__lruvec_stat_mod_folio(folio, NR_FILE_MAPPED, nr);
/* See comments in folio_add_anon_rmap_*() */
@@ -1545,7 +1545,7 @@ static __always_inline void __folio_remove_rmap(struct folio *folio,
/* NR_{FILE/SHMEM}_PMDMAPPED are not maintained per-memcg */
if (folio_test_anon(folio))
__lruvec_stat_mod_folio(folio, NR_ANON_THPS, -nr_pmdmapped);
- else
+ else if (likely(!(vma->vm_flags & VM_DMABUF_DIO)))
__mod_node_page_state(pgdat,
folio_test_swapbacked(folio) ?
NR_SHMEM_PMDMAPPED : NR_FILE_PMDMAPPED,
@@ -1553,7 +1553,8 @@ static __always_inline void __folio_remove_rmap(struct folio *folio,
}
if (nr) {
idx = folio_test_anon(folio) ? NR_ANON_MAPPED : NR_FILE_MAPPED;
- __lruvec_stat_mod_folio(folio, idx, -nr);
+ if (likely(!(vma->vm_flags & VM_DMABUF_DIO)))
+ __lruvec_stat_mod_folio(folio, idx, -nr);
/*
* Queue anon large folio for deferred split if at least one
--
2.34.1
