On Wed, Apr 01, 2015 at 03:06:53PM -0700, Andrew Morton wrote:
> On Thu, 2 Apr 2015 01:02:46 +0300 "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> wrote:
>
> > On Wed, Apr 01, 2015 at 12:57:45PM -0700, Andrew Morton wrote:
> > > On Wed, 1 Apr 2015 14:50:54 +0300 "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx> wrote:
> > >
> > > > >From adc384977898173d65c2567fc5eb421da9b272e0 Mon Sep 17 00:00:00 2001
> > > > From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
> > > > Date: Wed, 1 Apr 2015 14:33:56 +0300
> > > > Subject: [PATCH] mm: uninline and cleanup page-mapping related helpers
> > > >
> > > > Most-used page->mapping helper -- page_mapping() -- has already
> > > > uninlined. Let's uninline also page_rmapping() and page_anon_vma().
> > > > It saves us depending on configuration around 400 bytes in text:
> > > >
> > > > text data bss dec hex filename
> > > > 660318 99254 410000 1169572 11d8a4 mm/built-in.o-before
> > > > 659854 99254 410000 1169108 11d6d4 mm/built-in.o
> > >
> > > Well, code size isn't the only thing to care about. Some functions
> > > really should be inlined for performance reasons even if that makes the
> > > overall code larger. But the changes you're proposing here look OK to
> > > me.
> > >
> > > > As side effect page_anon_vma() now works properly on tail pages.
> > >
> > > Let's fix the bug in a separate patch, please. One which can be
> > > backported to earlier kernels if that should be needed. ie: it should
> > > precede any uninlining.
> >
> > The bug is not triggerable in current upsteam. AFAIK, we don't call
> > page_anon_vma() on tail pages of THP, since we don't map THP with PTEs
> > yet. For rest of cases we will get NULL, which is valid answer.
>
> argh. It rather helps if you can tell me when this happens (and which
> patch it fixes). I sometimes spend quite a bit of time runnnig around
> in circles wondering what the heck tree/patch just got fixed.
Sorry for the mess.
> > Do you still want "page = compound_head(page);" line in separate patch?
>
> I think that would be best. That way the offending patch gets fixed
> and doesn't get bundled up with an unrelated change.
I've sent updated "mm: sanitize page->mapping for tail pages" patch that
care about this part. And this is uninlining patch on top of updated
patch.
>From 17633731522fa958ee0cef5e125f06ea6ddafb08 Mon Sep 17 00:00:00 2001
From: "Kirill A. Shutemov" <kirill.shutemov@xxxxxxxxxxxxxxx>
Date: Wed, 1 Apr 2015 14:33:56 +0300
Subject: [PATCH] mm: uninline and cleanup page-mapping related helpers
Most-used page->mapping helper -- page_mapping() -- has already
uninlined. Let's uninline also page_rmapping() and page_anon_vma().
It saves us depending on configuration around 400 bytes in text:
text data bss dec hex filename
660318 99254 410000 1169572 11d8a4 mm/built-in.o-before
659854 99254 410000 1169108 11d6d4 mm/built-in.o
I also tried to make code a bit more clean.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
---
include/linux/mm.h | 9 ++-------
include/linux/rmap.h | 9 ---------
mm/util.c | 42 ++++++++++++++++++++++++++++++++++++------
3 files changed, 38 insertions(+), 22 deletions(-)
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 16fe322b66ea..eb19c939a216 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -910,15 +910,10 @@ void page_address_init(void);
#define page_address_init() do { } while(0)
#endif
+extern void *page_rmapping(struct page *page);
+extern struct anon_vma *page_anon_vma(struct page *page);
extern struct address_space *page_mapping(struct page *page);
-/* Neutral page->mapping pointer to address_space or anon_vma or other */
-static inline void *page_rmapping(struct page *page)
-{
- page = compound_head(page);
- return (void *)((unsigned long)page->mapping & ~PAGE_MAPPING_FLAGS);
-}
-
extern struct address_space *__page_file_mapping(struct page *);
static inline
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 6e7b0443afb0..c89c53a113a8 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -105,15 +105,6 @@ static inline void put_anon_vma(struct anon_vma *anon_vma)
__put_anon_vma(anon_vma);
}
-static inline struct anon_vma *page_anon_vma(struct page *page)
-{
- page = compound_head(page);
- if (((unsigned long)page->mapping & PAGE_MAPPING_FLAGS) !=
- PAGE_MAPPING_ANON)
- return NULL;
- return page_rmapping(page);
-}
-
static inline void vma_lock_anon_vma(struct vm_area_struct *vma)
{
struct anon_vma *anon_vma = vma->anon_vma;
diff --git a/mm/util.c b/mm/util.c
index e78968bd11e7..aca58b81bcfa 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -325,12 +325,39 @@ void kvfree(const void *addr)
}
EXPORT_SYMBOL(kvfree);
+static inline void * __page_rmapping(struct page *page)
+{
+ unsigned long mapping;
+
+ mapping = (unsigned long)page->mapping;
+ mapping &= ~PAGE_MAPPING_FLAGS;
+
+ return (void *)mapping;
+}
+
+/* Neutral page->mapping pointer to address_space or anon_vma or other */
+void *page_rmapping(struct page *page)
+{
+ page = compound_head(page);
+ return __page_rmapping(page);
+}
+
+struct anon_vma *page_anon_vma(struct page *page)
+{
+ unsigned long mapping;
+
+ page = compound_head(page);
+ mapping = (unsigned long)page->mapping;
+ if ((mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
+ return NULL;
+ return __page_rmapping(page);
+}
+
struct address_space *page_mapping(struct page *page)
{
- struct address_space *mapping;
+ unsigned long mapping;
page = compound_head(page);
- mapping = page->mapping;
/* This happens if someone calls flush_dcache_page on slab page */
if (unlikely(PageSlab(page)))
@@ -340,10 +367,13 @@ struct address_space *page_mapping(struct page *page)
swp_entry_t entry;
entry.val = page_private(page);
- mapping = swap_address_space(entry);
- } else if ((unsigned long)mapping & PAGE_MAPPING_ANON)
- mapping = NULL;
- return mapping;
+ return swap_address_space(entry);
+ }
+
+ mapping = (unsigned long)page->mapping;
+ if (mapping & PAGE_MAPPING_FLAGS)
+ return NULL;
+ return page->mapping;
}
int overcommit_ratio_handler(struct ctl_table *table, int write,
--
Kirill A. Shutemov
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