linux-stable.git/include/linux/mm_types.h, branch v4.17.2

mm: change return type to vm_fault_t

2018-04-06T04:36:27+00:00

The plan for these patches is to introduce the typedef, initially just
as documentation ("These functions should return a VM_FAULT_ status").
We'll trickle the patches to individual drivers/filesystems in through
the maintainers, as far as possible.  Then we'll change the typedef to
an unsigned int and break the compilation of any unconverted
drivers/filesystems.

vmf_insert_page(), vmf_insert_mixed() and vmf_insert_pfn() are three
newly added functions.  The various drivers/filesystems where return
value of fault(), huge_fault(), page_mkwrite() and pfn_mkwrite() get
converted, will need them.  These functions will return correct
VM_FAULT_ code based on err value.

We've had bugs before where drivers returned -EFOO.  And we have this
silly inefficiency where vm_insert_xxx() return an errno which (afaict)
every driver then converts into a VM_FAULT code.  In many cases drivers
failed to return correct VM_FAULT code value despite of vm_insert_xxx()
fails.  We have indentified and clean up all those existing bugs and
silly inefficiencies in driver/filesystems by adding these three new
inline wrappers.  As mentioned above, we will trickle those patches to
individual drivers/filesystems in through maintainers after these three
wrapper functions are merged.

Eventually we can convert vm_insert_xxx() into vmf_insert_xxx() and
remove these inline wrappers, but these are a good intermediate step.

Link: http://lkml.kernel.org/r/20180310162351.GA7422@jordon-HP-15-Notebook-PC
Signed-off-by: Souptick Joarder 
Acked-by: Michal Hocko 
Cc: Matthew Wilcox 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: remove reference to PG_buddy

2018-02-01T01:18:38+00:00

PG_buddy doesn't exist any more.  It's called PageBuddy now.

Link: http://lkml.kernel.org/r/20171220155552.15884-9-willy@infradead.org
Signed-off-by: Matthew Wilcox 
Acked-by: Kirill A. Shutemov 
Acked-by: Michal Hocko 
Acked-by: Christoph Lameter 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: document how to use struct page

2018-02-01T01:18:38+00:00

Be really explicit about what bits / bytes are reserved for users that
want to store extra information about the pages they allocate.

Link: http://lkml.kernel.org/r/20171220155552.15884-8-willy@infradead.org
Signed-off-by: Matthew Wilcox 
Acked-by: Kirill A. Shutemov 
Reviewed-by: Randy Dunlap 
Acked-by: Michal Hocko 
Cc: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: store compound_dtor / compound_order as bytes

2018-02-01T01:18:38+00:00

Neither of these values get even close to 256; compound_dtor is
currently at a maximum of 3, and compound_order can't be over 64.  No
machine has inefficient access to bytes since EV5, and while those are
still supported, we don't optimise for them any more.  This does not
shrink struct page, but it removes an ifdef and frees up 2-6 bytes for
future use.

diff of pahole output:

 		struct callback_head callback_head;      /*    32    16 */
 		struct {
 			long unsigned int compound_head; /*    32     8 */
-			unsigned int compound_dtor;      /*    40     4 */
-			unsigned int compound_order;     /*    44     4 */
+			unsigned char compound_dtor;     /*    40     1 */
+			unsigned char compound_order;    /*    41     1 */
 		};                                       /*    32    16 */
 	};                                               /*    32    16 */
 	union {

[mawilcox@microsoft.com: add comment]
  Link: http://lkml.kernel.org/r/20171221000144.GB2980@bombadil.infradead.org
Link: http://lkml.kernel.org/r/20171220155552.15884-7-willy@infradead.org
Signed-off-by: Matthew Wilcox 
Acked-by: Kirill A. Shutemov 
Acked-by: Michal Hocko 
Cc: Christoph Lameter 
Cc: Randy Dunlap 
Signed-off-by: Matthew Wilcox 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: introduce _slub_counter_t

2018-02-01T01:18:38+00:00

Instead of putting the ifdef in the middle of the definition of struct
page, pull it forward to the rest of the ifdeffery around the SLUB
cmpxchg_double optimisation.

Link: http://lkml.kernel.org/r/20171220155552.15884-6-willy@infradead.org
Signed-off-by: Matthew Wilcox 
Acked-by: Kirill A. Shutemov 
Acked-by: Michal Hocko 
Cc: Christoph Lameter 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: improve comment on page->mapping

2018-02-01T01:18:38+00:00

The comment on page->mapping is terse, and out of date (it does not
mention the possibility of PAGE_MAPPING_MOVABLE).  Instead, point the
interested reader to page-flags.h where there is a much better comment.

Link: http://lkml.kernel.org/r/20171220155552.15884-5-willy@infradead.org
Signed-off-by: Matthew Wilcox 
Acked-by: Kirill A. Shutemov 
Acked-by: Michal Hocko 
Acked-by: Christoph Lameter 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: remove misleading alignment claims

2018-02-01T01:18:38+00:00

The "third double word block" isn't on 32-bit systems.  The layout looks
like this:

	unsigned long flags;
	struct address_space *mapping
	pgoff_t index;
	atomic_t _mapcount;
	atomic_t _refcount;

which is 32 bytes on 64-bit, but 20 bytes on 32-bit.  Nobody is trying to
use the fact that it's double-word aligned today, so just remove the
misleading claims.

Link: http://lkml.kernel.org/r/20171220155552.15884-4-willy@infradead.org
Signed-off-by: Matthew Wilcox 
Acked-by: Kirill A. Shutemov 
Acked-by: Christoph Lameter 
Cc: Michal Hocko 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: de-indent struct page

2018-02-01T01:18:38+00:00

I found the struct { union { struct { union { struct { } } } } } layout
rather confusing.  Fortunately, there is an easier way to write this.

The innermost union is of four things which are the size of an int, so
the ones which are used by slab/slob/slub can be pulled up two levels to
be in the outermost union with 'counters'.  That leaves us with struct {
union { struct { atomic_t; atomic_t; } } } which has the same layout,
but is easier to read.

Output from the current git version of pahole, diffed with -uw to ignore
the whitespace changes from the indentation:

 	};						/*    16     8 */
 	union {
 		long unsigned int  counters;		/*    24     8 */
-		struct {
-			union {
-				atomic_t _mapcount;	/*    24     4 */
 				unsigned int active;	/*    24     4 */
 				struct {
 					unsigned int inuse:16; /*    24:16  4 */
@@ -21,7 +18,8 @@
 					unsigned int frozen:1; /*    24: 0  4 */
 				};			/*    24     4 */
 				int units;		/*    24     4 */
-			};				/*    24     4 */
+		struct {
+			atomic_t   _mapcount;		/*    24     4 */
 			atomic_t   _refcount;		/*    28     4 */
 		};					/*    24     8 */
 	};						/*    24     8 */

Link: http://lkml.kernel.org/r/20171220155552.15884-3-willy@infradead.org
Signed-off-by: Matthew Wilcox 
Acked-by: Kirill A. Shutemov 
Acked-by: Michal Hocko 
Acked-by: Christoph Lameter 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: align struct page more aesthetically

2018-02-01T01:18:38+00:00

Patch series "Restructure struct page", v2.

This series does not attempt any grand restructuring.  Instead, it cures
the worst of the indentitis, fixes the documentation and reduces the
ifdeffery.  The only layout change is compound_dtor and compound_order
are each reduced to one byte.

This patch (of 8):

Instead of an ifdef block at the end of the struct, which needed its own
comment, define _struct_page_alignment up at the top where it fits
nicely with the existing comment.

Link: http://lkml.kernel.org/r/20171220155552.15884-2-willy@infradead.org
Signed-off-by: Matthew Wilcox 
Acked-by: Kirill A. Shutemov 
Acked-by: Michal Hocko 
Acked-by: Christoph Lameter 
Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kmemcheck: remove annotations

2017-11-16T02:21:04+00:00

Patch series "kmemcheck: kill kmemcheck", v2.

As discussed at LSF/MM, kill kmemcheck.

KASan is a replacement that is able to work without the limitation of
kmemcheck (single CPU, slow).  KASan is already upstream.

We are also not aware of any users of kmemcheck (or users who don't
consider KASan as a suitable replacement).

The only objection was that since KASAN wasn't supported by all GCC
versions provided by distros at that time we should hold off for 2
years, and try again.

Now that 2 years have passed, and all distros provide gcc that supports
KASAN, kill kmemcheck again for the very same reasons.

This patch (of 4):

Remove kmemcheck annotations, and calls to kmemcheck from the kernel.

[alexander.levin@verizon.com: correctly remove kmemcheck call from dma_map_sg_attrs]
  Link: http://lkml.kernel.org/r/20171012192151.26531-1-alexander.levin@verizon.com
Link: http://lkml.kernel.org/r/20171007030159.22241-2-alexander.levin@verizon.com
Signed-off-by: Sasha Levin 
Cc: Alexander Potapenko 
Cc: Eric W. Biederman 
Cc: Michal Hocko 
Cc: Pekka Enberg 
Cc: Steven Rostedt 
Cc: Tim Hansen 
Cc: Vegard Nossum 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds