The patch titled
Subject: filemap: add filemap_map_order0_folio() to handle order0 folio
has been added to the -mm mm-hotfixes-unstable branch. Its filename is
filemap-add-filemap_map_order0_folio-to-handle-order0-folio.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/filemap-add-filemap_map_order0_folio-to-handle-order0-folio.patch
This patch will later appear in the mm-hotfixes-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Yin Fengwei <fengwei.yin@xxxxxxxxx>
Subject: filemap: add filemap_map_order0_folio() to handle order0 folio
Date: Thu, 14 Sep 2023 21:47:41 +0800
Kernel test robot reported regressions for several benchmarks [1].
The regression are related with commit:
de74976eb65151a2f568e477fc2e0032df5b22b4 ("filemap: add filemap_map_folio_range()")
It turned out that function filemap_map_folio_range() brings these
regressions when handle folio with order0.
Add filemap_map_order0_folio() to handle order0 folio. The benefit
come from two perspectives:
- the code size is smaller (around 126 bytes)
- no loop
Testing showed the regressions reported by 0day [1] all are fixed:
commit 9f1f5b60e76d44fa: parent commit of de74976eb65151a2
commit fbdf9263a3d7fdbd: latest mm-unstable commit
commit 7fbfe2003f84686d: this fixing patch
9f1f5b60e76d44fa fbdf9263a3d7fdbd 7fbfe2003f84686d
---------------- --------------------------- ---------------------------
3843810 -21.4% 3020268 +4.6% 4018708 stress-ng.bad-altstack.ops
64061 -21.4% 50336 +4.6% 66977 stress-ng.bad-altstack.ops_per_sec
1709026 -14.4% 1462102 +2.4% 1750757 stress-ng.fork.ops
28483 -14.4% 24368 +2.4% 29179 stress-ng.fork.ops_per_sec
3685088 -53.6% 1710976 +0.5% 3702454 stress-ng.zombie.ops
56732 -65.3% 19667 +0.7% 57107 stress-ng.zombie.ops_per_sec
61874 -12.1% 54416 +0.4% 62136 vm-scalability.median
13527663 -11.7% 11942117 -0.1% 13513946 vm-scalability.throughput
4.066e+09 -11.7% 3.59e+09 -0.1% 4.061e+09 vm-scalability.workload
[1]:
https://lore.kernel.org/oe-lkp/72e017b9-deb6-44fa-91d6-716ee2c39cbc@xxxxxxxxx/T/#m7d2bba30f75a9cee8eab07e5809abd9b3b206c84
Link: https://lkml.kernel.org/r/20230914134741.1937654-1-fengwei.yin@xxxxxxxxx
Fixes: de74976eb65151a2f568e477fc2e0032df5b22b4 ("filemap: add filemap_map_folio_range()")
Signed-off-by: Yin Fengwei <fengwei.yin@xxxxxxxxx>
Reported-by: kernel test robot <oliver.sang@xxxxxxxxx>
Closes: https://lore.kernel.org/oe-lkp/202309111556.b2aa3d7a-oliver.sang@xxxxxxxxx
Cc: Feng Tang <feng.tang@xxxxxxxxx>
Cc: Huang Ying <ying.huang@xxxxxxxxx>
Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/filemap.c | 69 ++++++++++++++++++++++++++++++++++---------------
1 file changed, 48 insertions(+), 21 deletions(-)
--- a/mm/filemap.c~filemap-add-filemap_map_order0_folio-to-handle-order0-folio
+++ a/mm/filemap.c
@@ -3475,13 +3475,11 @@ skip:
*/
static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
struct folio *folio, unsigned long start,
- unsigned long addr, unsigned int nr_pages)
+ unsigned long addr, unsigned int nr_pages,
+ unsigned int *mmap_miss)
{
vm_fault_t ret = 0;
- struct vm_area_struct *vma = vmf->vma;
- struct file *file = vma->vm_file;
struct page *page = folio_page(folio, start);
- unsigned int mmap_miss = READ_ONCE(file->f_ra.mmap_miss);
unsigned int count = 0;
pte_t *old_ptep = vmf->pte;
@@ -3489,8 +3487,7 @@ static vm_fault_t filemap_map_folio_rang
if (PageHWPoison(page + count))
goto skip;
- if (mmap_miss > 0)
- mmap_miss--;
+ (*mmap_miss)++;
/*
* NOTE: If there're PTE markers, we'll leave them to be
@@ -3525,7 +3522,35 @@ skip:
}
vmf->pte = old_ptep;
- WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss);
+
+ return ret;
+}
+
+static vm_fault_t filemap_map_order0_folio(struct vm_fault *vmf,
+ struct folio *folio, unsigned long addr,
+ unsigned int *mmap_miss)
+{
+ vm_fault_t ret = 0;
+ struct page *page = &folio->page;
+
+ if (PageHWPoison(page))
+ return ret;
+
+ (*mmap_miss)++;
+
+ /*
+ * NOTE: If there're PTE markers, we'll leave them to be
+ * handled in the specific fault path, and it'll prohibit
+ * the fault-around logic.
+ */
+ if (!pte_none(ptep_get(vmf->pte)))
+ return ret;
+
+ if (vmf->address == addr)
+ ret = VM_FAULT_NOPAGE;
+
+ set_pte_range(vmf, folio, page, 1, addr);
+ folio_ref_inc(folio);
return ret;
}
@@ -3541,7 +3566,7 @@ vm_fault_t filemap_map_pages(struct vm_f
XA_STATE(xas, &mapping->i_pages, start_pgoff);
struct folio *folio;
vm_fault_t ret = 0;
- int nr_pages = 0;
+ unsigned int nr_pages = 0, mmap_miss = 0, mmap_miss_saved;
rcu_read_lock();
folio = next_uptodate_folio(&xas, mapping, end_pgoff);
@@ -3569,25 +3594,27 @@ vm_fault_t filemap_map_pages(struct vm_f
end = folio->index + folio_nr_pages(folio) - 1;
nr_pages = min(end, end_pgoff) - xas.xa_index + 1;
- /*
- * NOTE: If there're PTE markers, we'll leave them to be
- * handled in the specific fault path, and it'll prohibit the
- * fault-around logic.
- */
- if (!pte_none(ptep_get(vmf->pte)))
- goto unlock;
-
- ret |= filemap_map_folio_range(vmf, folio,
- xas.xa_index - folio->index, addr, nr_pages);
+ if (!folio_test_large(folio))
+ ret |= filemap_map_order0_folio(vmf,
+ folio, addr, &mmap_miss);
+ else
+ ret |= filemap_map_folio_range(vmf, folio,
+ xas.xa_index - folio->index, addr,
+ nr_pages, &mmap_miss);
-unlock:
folio_unlock(folio);
folio_put(folio);
- folio = next_uptodate_folio(&xas, mapping, end_pgoff);
- } while (folio);
+ } while ((folio = next_uptodate_folio(&xas, mapping, end_pgoff)) != NULL);
pte_unmap_unlock(vmf->pte, vmf->ptl);
out:
rcu_read_unlock();
+
+ mmap_miss_saved = READ_ONCE(file->f_ra.mmap_miss);
+ if (mmap_miss >= mmap_miss_saved)
+ WRITE_ONCE(file->f_ra.mmap_miss, 0);
+ else
+ WRITE_ONCE(file->f_ra.mmap_miss, mmap_miss_saved - mmap_miss);
+
return ret;
}
EXPORT_SYMBOL(filemap_map_pages);
_
Patches currently in -mm which might be from fengwei.yin@xxxxxxxxx are
filemap-add-filemap_map_order0_folio-to-handle-order0-folio.patch
