linux/include
Christoph Lameter d85f33855c Make page->private usable in compound pages
If we add a new flag so that we can distinguish between the first page and the
tail pages then we can avoid to use page->private in the first page.
page->private == page for the first page, so there is no real information in
there.

Freeing up page->private makes the use of compound pages more transparent.
They become more usable like real pages.  Right now we have to be careful f.e.
 if we are going beyond PAGE_SIZE allocations in the slab on i386 because we
can then no longer use the private field.  This is one of the issues that
cause us not to support debugging for page size slabs in SLAB.

Having page->private available for SLUB would allow more meta information in
the page struct.  I can probably avoid the 16 bit ints that I have in there
right now.

Also if page->private is available then a compound page may be equipped with
buffer heads.  This may free up the way for filesystems to support larger
blocks than page size.

We add PageTail as an alias of PageReclaim.  Compound pages cannot currently
be reclaimed.  Because of the alias one needs to check PageCompound first.

The RFC for the this approach was discussed at
http://marc.info/?t=117574302800001&r=1&w=2

[nacc@us.ibm.com: fix hugetlbfs]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-07 12:12:53 -07:00
..
acpi remove "struct subsystem" as it is no longer needed 2007-05-02 18:57:59 -07:00
asm-alpha Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-arm Merge branch 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm 2007-05-06 13:20:10 -07:00
asm-arm26 [PATCH] x86: PARAVIRT: add hooks to intercept mm creation and destruction 2007-05-02 19:27:14 +02:00
asm-avr32 Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-cris [PATCH] x86: PARAVIRT: add hooks to intercept mm creation and destruction 2007-05-02 19:27:14 +02:00
asm-frv Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-generic [PATCH] i386: Clean up ELF note generation 2007-05-02 19:27:17 +02:00
asm-h8300 Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-i386 i386: use page allocator to allocate thread_info structure 2007-05-07 12:12:53 -07:00
asm-ia64 Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-m32r Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-m68k Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-m68knommu Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-mips Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-parisc Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-powerpc Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-ppc [PATCH] x86: PARAVIRT: add hooks to intercept mm creation and destruction 2007-05-02 19:27:14 +02:00
asm-s390 Introduce CONFIG_HAS_DMA 2007-05-07 12:12:51 -07:00
asm-sh Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-sh64 Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-sparc [PATCH] x86: PARAVIRT: add hooks to intercept mm creation and destruction 2007-05-02 19:27:14 +02:00
asm-sparc64 Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-um [PATCH] x86: PARAVIRT: add hooks to intercept mm creation and destruction 2007-05-02 19:27:14 +02:00
asm-v850 Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
asm-x86_64 Revert "[PATCH] x86: __pa and __pa_symbol address space separation" 2007-05-07 08:44:24 -07:00
asm-xtensa Merge branch 'for-linus' of git://one.firstfloor.org/home/andi/git/linux-2.6 2007-05-05 14:55:20 -07:00
crypto [CRYPTO] cryptd: Add software async crypto daemon 2007-05-02 14:38:32 +10:00
keys [AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both 2007-04-26 15:48:28 -07:00
linux Make page->private usable in compound pages 2007-05-07 12:12:53 -07:00
math-emu
media i2c: Cleanup the includes of <linux/i2c.h> 2007-05-01 23:26:29 +02:00
mtd UBI: Unsorted Block Images 2007-04-27 14:23:33 +03:00
net [MAC80211]: Add mac80211 wireless stack. 2007-05-05 11:45:53 -07:00
pcmcia add new_id to PCMCIA drivers 2007-05-07 12:12:50 -07:00
rdma PCI: Cleanup the includes of <linux/pci.h> 2007-05-02 19:02:35 -07:00
rxrpc [AF_RXRPC]: Delete the old RxRPC code. 2007-04-26 15:55:48 -07:00
scsi [SCSI] modalias for scsi devices 2007-04-17 18:15:04 -04:00
sound [ALSA] version 1.0.14rc3 2007-03-14 08:25:52 +01:00
video
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