On 2024/7/1 16:40, Ryan Roberts wrote:
On 01/07/2024 09:33, Baolin Wang wrote:
On 2024/7/1 15:55, Ryan Roberts wrote:
On 28/06/2024 11:49, Bang Li wrote:
After the commit 7fb1b252afb5 ("mm: shmem: add mTHP support for
anonymous shmem"), we can configure different policies through
the multi-size THP sysfs interface for anonymous shmem. But
currently "THPeligible" indicates only whether the mapping is
eligible for allocating THP-pages as well as the THP is PMD
mappable or not for anonymous shmem, we need to support semantics
for mTHP with anonymous shmem similar to those for mTHP with
anonymous memory.
Signed-off-by: Bang Li <libang.li@xxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 10 +++++++---
include/linux/huge_mm.h | 11 +++++++++++
mm/shmem.c | 9 +--------
3 files changed, 19 insertions(+), 11 deletions(-)
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 93fb2c61b154..09b5db356886 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -870,6 +870,7 @@ static int show_smap(struct seq_file *m, void *v)
{
struct vm_area_struct *vma = v;
struct mem_size_stats mss = {};
+ bool thp_eligible;
smap_gather_stats(vma, &mss, 0);
@@ -882,9 +883,12 @@ static int show_smap(struct seq_file *m, void *v)
__show_smap(m, &mss, false);
- seq_printf(m, "THPeligible: %8u\n",
- !!thp_vma_allowable_orders(vma, vma->vm_flags,
- TVA_SMAPS | TVA_ENFORCE_SYSFS, THP_ORDERS_ALL));
+ thp_eligible = !!thp_vma_allowable_orders(vma, vma->vm_flags,
+ TVA_SMAPS | TVA_ENFORCE_SYSFS, THP_ORDERS_ALL);
+ if (vma_is_anon_shmem(vma))
+ thp_eligible = !!shmem_allowable_huge_orders(file_inode(vma->vm_file),
+ vma, vma->vm_pgoff, thp_eligible);
Afraid I haven't been following the shmem mTHP support work as much as I would
have liked, but is there a reason why we need a separate function for shmem?
Since shmem_allowable_huge_orders() only uses shmem specific logic to determine
if huge orders are allowable, there is no need to complicate the
thp_vma_allowable_orders() function by adding more shmem related logic, making
it more bloated. In my view, providing a dedicated helper
shmem_allowable_huge_orders(), specifically for shmem, simplifies the logic.
My point was really that a single interface (thp_vma_allowable_orders) should be
used to get this information. I have no strong opinon on how the implementation
of that interface looks. What you suggest below seems perfectly reasonable to me.
IIUC, I agree with David's suggestion that the shmem_allowable_huge_orders()
helper function could be used in thp_vma_allowable_orders() to support shmem
mTHP. Something like:
I hadn't seen David's suggestion until after I sent my mail. But I think we are > both suggesting the same thing.
OK. Great :)
