Revision 340b3a5b35c0919e1535b355a9eafe1f81c4cae3 authored by Linus Torvalds on 28 February 2016, 00:58:32 UTC, committed by Linus Torvalds on 28 February 2016, 00:58:32 UTC
Pull ARM SoC fixes from Olof Johansson:
"We didn't have a batch last week, so this one is slightly larger.
None of them are scary though, a handful of fixes for small DT pieces,
replacing properties with newer conventions.
Highlights:
- N900 fix for setting system revision
- onenand init fix to avoid filesystem corruption
- Clock fix for audio on Beaglebone-x15
- Fixes on shmobile to deal with CONFIG_DEBUG_RODATA (default y in 4.6)
+ misc smaller stuff"
* tag 'armsoc-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
MAINTAINERS: Extend info, add wiki and ml for meson arch
MAINTAINERS: alpine: add a new maintainer and update the entry
ARM: at91/dt: fix typo in sama5d2 pinmux descriptions
ARM: OMAP2+: Fix onenand initialization to avoid filesystem corruption
Revert "regulator: tps65217: remove tps65217.dtsi file"
ARM: shmobile: Remove shmobile_boot_arg
ARM: shmobile: Move shmobile_smp_{mpidr, fn, arg}[] from .text to .bss
ARM: shmobile: r8a7779: Remove remainings of removed SCU boot setup code
ARM: shmobile: Move shmobile_scu_base from .text to .bss
ARM: OMAP2+: Fix omap_device for module reload on PM runtime forbid
ARM: OMAP2+: Improve omap_device error for driver writers
ARM: DTS: am57xx-beagle-x15: Select SYS_CLK2 for audio clocks
ARM: dts: am335x/am57xx: replace gpio-key,wakeup with wakeup-source property
ARM: OMAP2+: Set system_rev from ATAGS for n900
ARM: dts: orion5x: fix the missing mtd flash on linkstation lswtgl
ARM: dts: kirkwood: use unique machine name for ds112
ARM: dts: imx6: remove bogus interrupt-parent from CAAM node
remap_file_pages.txt
The remap_file_pages() system call is used to create a nonlinear mapping,
that is, a mapping in which the pages of the file are mapped into a
nonsequential order in memory. The advantage of using remap_file_pages()
over using repeated calls to mmap(2) is that the former approach does not
require the kernel to create additional VMA (Virtual Memory Area) data
structures.
Supporting of nonlinear mapping requires significant amount of non-trivial
code in kernel virtual memory subsystem including hot paths. Also to get
nonlinear mapping work kernel need a way to distinguish normal page table
entries from entries with file offset (pte_file). Kernel reserves flag in
PTE for this purpose. PTE flags are scarce resource especially on some CPU
architectures. It would be nice to free up the flag for other usage.
Fortunately, there are not many users of remap_file_pages() in the wild.
It's only known that one enterprise RDBMS implementation uses the syscall
on 32-bit systems to map files bigger than can linearly fit into 32-bit
virtual address space. This use-case is not critical anymore since 64-bit
systems are widely available.
The syscall is deprecated and replaced it with an emulation now. The
emulation creates new VMAs instead of nonlinear mappings. It's going to
work slower for rare users of remap_file_pages() but ABI is preserved.
One side effect of emulation (apart from performance) is that user can hit
vm.max_map_count limit more easily due to additional VMAs. See comment for
DEFAULT_MAX_MAP_COUNT for more details on the limit.
Computing file changes ...
