Linus Torvalds 89f5b7da2a Reinstate ZERO_PAGE optimization in 'get_user_pages()' and fix XIP ... KAMEZAWA Hiroyuki and Oleg Nesterov point out that since the commit 557ed1fa26 ("remove ZERO_PAGE") removed the ZERO_PAGE from the VM mappings, any users of get_user_pages() will generally now populate the VM with real empty pages needlessly. We used to get the ZERO_PAGE when we did the "handle_mm_fault()", but since fault handling no longer uses ZERO_PAGE for new anonymous pages, we now need to handle that special case in follow_page() instead. In particular, the removal of ZERO_PAGE effectively removed the core file writing optimization where we would skip writing pages that had not been populated at all, and increased memory pressure a lot by allocating all those useless newly zeroed pages. This reinstates the optimization by making the unmapped PTE case the same as for a non-existent page table, which already did this correctly. While at it, this also fixes the XIP case for follow_page(), where the caller could not differentiate between the case of a page that simply could not be used (because it had no "struct page" associated with it) and a page that just wasn't mapped. We do that by simply returning an error pointer for pages that could not be turned into a "struct page *". The error is arbitrarily picked to be EFAULT, since that was what get_user_pages() already used for the equivalent IO-mapped page case. [ Also removed an impossible test for pte_offset_map_lock() failing: that's not how that function works ] Acked-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: Nick Piggin <npiggin@suse.de> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> Cc: Hugh Dickins <hugh@veritas.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Ingo Molnar <mingo@elte.hu> Cc: Roland McGrath <roland@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>		2008-06-20 11:18:25 -07:00
..
vdso32	[POWERPC] vdso: Fixes for cache block sizes	2007-11-20 13:56:31 +11:00
vdso64	[POWERPC] vdso: Fixes for cache block sizes	2007-11-20 13:56:31 +11:00
align.c
asm-offsets.c	Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc	2008-04-29 08:19:14 -07:00
audit.c
btext.c	[POWERPC] Remove duplicate #include	2008-05-09 20:22:58 +10:00
clock.c
compat_audit.c
cpu_setup_6xx.S	[POWERPC] ppc32: Fix errata for 603 CPUs	2008-04-21 15:00:32 -05:00
cpu_setup_44x.S	[POWERPC] 4xx: Fix 460GT support to not enable FPU	2008-04-24 13:32:47 -05:00
cpu_setup_pa6t.S
cpu_setup_ppc970.S
cputable.c	[POWERPC] Fix default cputable entries for e200 and e500 families	2008-05-12 14:20:35 +10:00
crash_dump.c	[LIB]: Make PowerPC LMB code generic so sparc64 can use it too.	2008-02-13 16:56:49 -08:00
crash.c	[LIB]: Make PowerPC LMB code generic so sparc64 can use it too.	2008-02-13 16:56:49 -08:00
dma_64.c	iommu sg: powerpc: convert iommu to use the IOMMU helper	2008-02-05 09:44:11 -08:00
entry_32.S	[POWERPC] Add IRQSTACKS support on ppc32	2008-04-29 15:57:34 +10:00
entry_64.S	[POWERPC] irqtrace support for 64-bit powerpc	2008-04-18 15:38:47 +10:00
firmware.c
fpu.S
head_8xx.S	[POWERPC] 8xx: fix swap	2008-03-07 08:42:28 -06:00
head_32.S	[POWERPC] Move stackframe definitions to common header	2008-04-18 15:37:18 +10:00
head_40x.S	[POWERPC] Fix swapper_pg_dir size when CONFIG_PTE_64BIT=y on FSL_BOOKE	2007-12-06 13:11:04 -06:00
head_44x.S	[POWERPC] 4xx: Clear new TLB cache attribute bits in Data Storage vector	2008-06-18 21:40:43 +10:00
head_64.S	[POWERPC] Fix bogus paca->_current initialization	2008-05-09 20:22:58 +10:00
head_booke.h	[POWERPC] Rework Book-E debug exception handling	2008-04-17 01:01:36 -05:00
head_fsl_booke.S	[POWERPC] 85xx: Add support for relocatable kernel (and booting at non-zero)	2008-04-24 20:58:01 +10:00
ibmebus.c	[POWERPC] Replace remaining __FUNCTION__ occurrences	2008-04-01 20:43:09 +11:00
idle_6xx.S
idle_power4.S
idle.c	[POWERPC] Fix sysctl table check failure on PowerMac	2007-11-08 14:15:30 +11:00
init_task.c	[PATCH] take init_files to fs/file.c	2008-05-16 17:22:20 -04:00
io.c
iomap.c
iommu.c	[POWERPC] Replace remaining __FUNCTION__ occurrences	2008-04-01 20:43:09 +11:00
irq.c	[POWERPC] Fix return value check logic in debugfs virq_mapping setup	2008-06-16 15:00:25 +10:00
isa-bridge.c	[POWERPC] Remove leftover printk in isa-bridge.c	2008-05-09 20:22:59 +10:00
kprobes.c	[POWERPC] Kill sparse warnings in kprobes	2008-02-20 13:33:37 +11:00
l2cr_6xx.S	Convert files to UTF-8 and some cleanups	2007-10-19 23:21:04 +02:00
legacy_serial.c	[POWERPC] Fix legacy serial search for opb bus ports	2008-02-06 16:30:00 +11:00
lparcfg.c	powerpc: use non-racy method for proc entries creation	2008-04-29 08:06:22 -07:00
machine_kexec_32.c
machine_kexec_64.c
machine_kexec.c	[POWERPC] Fix crashkernel= handling when no crashkernel= specified	2008-04-30 19:49:48 +10:00
Makefile	[POWERPC] ppc: Don't run prom_init_check for arch/ppc builds	2008-05-12 20:27:50 +10:00
misc_32.S	[POWERPC] Add IRQSTACKS support on ppc32	2008-04-29 15:57:34 +10:00
misc_64.S	[POWERPC] Clean up misc_64.S	2008-04-24 20:58:03 +10:00
misc.S	[POWERPC] Make setjmp/longjmp code usable outside of xmon	2008-01-25 22:52:50 +11:00
module_32.c	[POWERPC] Optimize counting distinct entries in the relocation sections	2007-12-21 15:05:58 +11:00
module_64.c	[POWERPC] Optimize counting distinct entries in the relocation sections	2007-12-21 15:05:58 +11:00
msi.c
nvram_64.c
of_device.c	[POWERPC] Use <linux/of_{platform, device}.h> and not <asm/...> variants.	2008-01-17 14:58:57 +11:00
of_platform.c	[POWERPC] cell: Generalize io-workarounds code	2008-04-24 21:08:12 +10:00
paca.c	[POWERPC] Raise the upper limit of NR_CPUS and move the pacas into the BSS	2008-04-24 20:58:04 +10:00
pci_32.c	[POWERPC] Remove update_bridge_resource	2008-01-23 19:32:30 -06:00
pci_64.c	[POWERPC] Use dev_set_name in pci_64.c	2008-06-09 11:32:40 +10:00
pci_dn.c	[POWERPC] iSeries: eliminate pci_dn bussubno	2008-01-17 14:57:05 +11:00
pci-common.c	PCI: powerpc: use generic pci_enable_resources()	2008-04-20 21:47:05 -07:00
pmc.c	[POWERPC] Made FSL Book-E PMC support more generic	2008-02-05 23:34:14 -06:00
ppc32.h	Revert "[POWERPC] Add compat handler for PTRACE_GETSIGINFO"	2008-04-24 14:05:15 +10:00
ppc_ksyms.c	[POWERPC] Remove ppc32's export of console_drivers	2008-06-16 15:00:56 +10:00
proc_ppc64.c	powerpc: use non-racy method for proc entries creation	2008-04-29 08:06:22 -07:00
process.c	[POWERPC] Add IRQSTACKS support on ppc32	2008-04-29 15:57:34 +10:00
prom_init_check.sh	[POWERPC] Fix -Os kernel builds with newer gcc versions	2008-06-16 15:00:54 +10:00
prom_init.c	[POWERPC] Efika: Really, don't pretend to be CHRP	2008-04-17 07:46:12 +10:00
prom_parse.c	[POWERPC] Add of_translate_dma_address	2007-12-11 15:43:35 +11:00
prom.c	[POWERPC] 85xx: Add support for relocatable kernel (and booting at non-zero)	2008-04-24 20:58:01 +10:00
ptrace32.c	Revert "[POWERPC] Add compat handler for PTRACE_GETSIGINFO"	2008-04-24 14:05:15 +10:00
ptrace.c	[POWERPC] user_regset PTRACE_SETREGS regression fix	2008-03-20 10:10:56 +11:00
rtas_flash.c	powerpc: use non-racy method for proc entries creation	2008-04-29 08:06:22 -07:00
rtas_pci.c	[POWERPC] Convert pci and eeh code to of_device_is_available	2008-04-07 13:49:25 +10:00
rtas-proc.c	powerpc: use non-racy method for proc entries creation	2008-04-29 08:06:22 -07:00
rtas-rtc.c
rtas.c	Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc	2008-04-21 15:50:49 -07:00
setup_32.c	[POWERPC] Add IRQSTACKS support on ppc32	2008-04-29 15:57:34 +10:00
setup_64.c	[POWERPC] Initialize lockdep earlier	2008-05-09 20:22:58 +10:00
setup-common.c	[POWERPC] Add 'model: ...' line to common show_cpuinfo()	2008-03-26 08:44:04 +11:00
setup.h
signal_32.c	[POWERPC] Define copy_siginfo_from_user32	2008-04-20 13:03:36 +10:00
signal_64.c	[POWERPC] Fix incorrect enabling of VMX when building signal or user context	2008-06-09 11:32:36 +10:00
signal.c
signal.h
smp-tbsync.c
smp.c	[POWERPC] Bolt in SLB entry for kernel stack on secondary cpus	2008-05-02 15:00:45 +10:00
softemu8xx.c
stacktrace.c	[POWERPC] Fix new warnings arising from stacktrace patch	2008-04-24 20:58:02 +10:00
suspend.c
swsusp_32.S	[POWERPC] Make altivec code in swsusp_32.S depend on CONFIG_ALTIVEC	2007-11-08 14:15:34 +11:00
swsusp_64.c
swsusp_asm64.S
swsusp.c
sys_ppc32.c	Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc	2008-04-21 15:50:49 -07:00
syscalls.c	unified (weak) sys_pipe implementation	2008-05-03 13:50:33 -07:00
sysfs.c	remove __attribute_used__	2008-01-28 23:21:18 +01:00
systbl_chk.c	[POWERPC] Fix a couple of copyright symbols	2008-01-25 22:52:50 +11:00
systbl_chk.sh	[POWERPC] Fix a couple of copyright symbols	2008-01-25 22:52:50 +11:00
systbl.S
tau_6xx.c
time.c	ntp: rename TICK_LENGTH_SHIFT to NTP_SCALE_SHIFT	2008-05-01 08:03:59 -07:00
traps.c	[POWERPC] Fix compilation for CONFIG_DEBUGGER=n and CONFIG_KEXEC=y	2008-02-07 11:40:18 +11:00
udbg_16550.c	[POWERPC] 4xx: Add early udbg support for 40x processors	2007-12-23 13:13:03 -06:00
udbg.c	[POWERPC] Mark udbg console as CON_ANYTIME, ie. callable early in boot	2008-04-24 21:08:11 +10:00
vdso.c	Reinstate ZERO_PAGE optimization in 'get_user_pages()' and fix XIP	2008-06-20 11:18:25 -07:00
vecemu.c
vector.S
vio.c	[POWERPC] Replace remaining __FUNCTION__ occurrences	2008-04-01 20:43:09 +11:00
vmlinux.lds.S	[POWERPC] Update linker script to properly set physical addresses	2008-04-17 07:46:14 +10:00