Evictable pages are divided into multiple generations for each lruvec.
The youngest generation number is stored in lrugen->max_seq for both
anon and file types as they are aged on an equal footing. The oldest
generation numbers are stored in lrugen->min_seq[] separately for anon
and file types as clean file pages can be evicted regardless of swap
constraints. These three variables are monotonically increasing.
Generation numbers are truncated into order_base_2(MAX_NR_GENS+1) bits
in order to fit into the gen counter in page->flags. Each truncated
generation number is an index to lrugen->lists[]. The sliding window
technique is used to track at least MIN_NR_GENS and at most
MAX_NR_GENS generations. The gen counter stores a value within [1,
MAX_NR_GENS] while a page is on one of lrugen->lists[]. Otherwise it
stores 0.
There are two conceptually independent procedures: "the aging", which
produces young generations, and "the eviction", which consumes old
generations. They form a closed-loop system, i.e., "the page reclaim".
Both procedures can be invoked from userspace for the purposes of
working set estimation and proactive reclaim. These features are
required to optimize job scheduling (bin packing) in data centers. The
variable size of the sliding window is designed for such use cases
[1][2].
To avoid confusion, the terms "hot" and "cold" will be applied to the
multi-gen LRU, as a new convention; the terms "active" and "inactive"
will be applied to the active/inactive LRU, as usual.
The protection of hot pages and the selection of cold pages are based
on page access channels and patterns. There are two access channels:
one through page tables and the other through file descriptors. The
protection of the former channel is by design stronger because:
1. The uncertainty in determining the access patterns of the former
channel is higher due to the approximation of the accessed bit.
2. The cost of evicting the former channel is higher due to the TLB
flushes required and the likelihood of encountering the dirty bit.
3. The penalty of underprotecting the former channel is higher because
applications usually do not prepare themselves for major page
faults like they do for blocked I/O. E.g., GUI applications
commonly use dedicated I/O threads to avoid blocking the rendering
threads.
There are also two access patterns: one with temporal locality and the
other without. For the reasons listed above, the former channel is
assumed to follow the former pattern unless VM_SEQ_READ or
VM_RAND_READ is present; the latter channel is assumed to follow the
latter pattern unless outlying refaults have been observed [3][4].
The next patch will address the "outlying refaults". Three macros,
i.e., LRU_REFS_WIDTH, LRU_REFS_PGOFF and LRU_REFS_MASK, used later are
added in this patch to make the entire patchset less diffy.
A page is added to the youngest generation on faulting. The aging
needs to check the accessed bit at least twice before handing this
page over to the eviction. The first check takes care of the accessed
bit set on the initial fault; the second check makes sure this page
has not been used since then. This protocol, AKA second chance,
requires a minimum of two generations, hence MIN_NR_GENS.
[1] https://dl.acm.org/doi/10.1145/3297858.3304053
[2] https://dl.acm.org/doi/10.1145/3503222.3507731
[3] https://lwn.net/Articles/495543/
[4] https://lwn.net/Articles/815342/
Link: https://lore.kernel.org/r/20220309021230.721028-6-yuzhao@google.com/
Signed-off-by: Yu Zhao <yuzhao@google.com>
Acked-by: Brian Geffon <bgeffon@google.com>
Acked-by: Jan Alexander Steffens (heftig) <heftig@archlinux.org>
Acked-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Acked-by: Steven Barrett <steven@liquorix.net>
Acked-by: Suleiman Souhlal <suleiman@google.com>
Tested-by: Daniel Byrne <djbyrne@mtu.edu>
Tested-by: Donald Carr <d@chaos-reins.com>
Tested-by: Holger Hoffstätte <holger@applied-asynchrony.com>
Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru>
Tested-by: Shuang Zhai <szhai2@cs.rochester.edu>
Tested-by: Sofia Trinh <sofia.trinh@edi.works>
Tested-by: Vaibhav Jain <vaibhav@linux.ibm.com>
Bug: 228114874
Change-Id: I333ec6a1d2abfa60d93d6adc190ed3eefe441512
Signed-off-by: azrim <mirzaspc@gmail.com>
For each lruvec, evictable pages are divided into multiple
generations. The youngest generation number is stored in
lrugen->max_seq for both anon and file types as they are aged on an
equal footing. The oldest generation numbers are stored in
lrugen->min_seq[2] separately for anon and file types as clean file
pages can be evicted regardless of may_swap or may_writepage. These
three variables are monotonically increasing. Generation numbers are
truncated into order_base_2(MAX_NR_GENS+1) bits in order to fit into
page->flags. The sliding window technique is used to prevent truncated
generation numbers from overlapping. Each truncated generation number
is an index to
lrugen->lists[MAX_NR_GENS][ANON_AND_FILE][MAX_NR_ZONES]. Evictable
pages are added to the per-zone lists indexed by lrugen->max_seq or
lrugen->min_seq[2] (modulo MAX_NR_GENS), depending on their types.
Each generation is then divided into multiple tiers. Tiers represent
levels of usage from file descriptors only. Pages accessed N times via
file descriptors belong to tier order_base_2(N). Each generation
contains at most MAX_NR_TIERS tiers, and they require additional
MAX_NR_TIERS-2 bits in page->flags. In contrast to moving across
generations which requires the lru lock for the list operations,
moving across tiers only involves an atomic operation on page->flags
and therefore has a negligible cost. A feedback loop modeled after the
PID controller monitors the refault rates across all tiers and decides
when to activate pages from which tiers in the reclaim path.
The framework comprises two conceptually independent components: the
aging and the eviction, which can be invoked separately from user
space for the purpose of working set estimation and proactive reclaim.
The aging produces young generations. Given an lruvec, the aging scans
page tables for referenced pages of this lruvec. Upon finding one, the
aging updates its generation number to max_seq. After each round of
scan, the aging increments max_seq. The aging is due when both of
min_seq[2] reaches max_seq-1, assuming both anon and file types are
reclaimable.
The eviction consumes old generations. Given an lruvec, the eviction
scans the pages on the per-zone lists indexed by either of min_seq[2].
It tries to select a type based on the values of min_seq[2] and
swappiness. During a scan, the eviction sorts pages according to their
new generation numbers, if the aging has found them referenced. When
it finds all the per-zone lists of a selected type are empty, the
eviction increments min_seq[2] indexed by this selected type.
Signed-off-by: Yu Zhao <yuzhao@google.com>
Tested-by: Konstantin Kharlamov <Hi-Angel@yandex.ru>
(am from https://lore.kernel.org/patchwork/patch/1432182/)
BUG=b:123039911
TEST=Built
Change-Id: I71de7cd15b8dfa6f9fdd838023474693c4fee0a7
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/kernel/+/2928251
Reviewed-by: Yu Zhao <yuzhao@chromium.org>
Reviewed-by: Sonny Rao <sonnyrao@chromium.org>
Tested-by: Yu Zhao <yuzhao@chromium.org>
Commit-Queue: Yu Zhao <yuzhao@chromium.org>
Signed-off-by: azrim <mirzaspc@gmail.com>
Most of the mm subsystem uses pr_<level> so make it consistent.
Miscellanea:
- Realign arguments
- Add missing newline to format
- kmemleak-test.c has a "kmemleak: " prefix added to the
"Kmemleak testing" logging message via pr_fmt
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Tejun Heo <tj@kernel.org> [percpu]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mminit_verify_page_links() is an extremely paranoid check that was
introduced when memory initialisation was being heavily reworked.
Profiles indicated that up to 10% of parallel memory initialisation was
spent on checking this for every page. The cost could be reduced but in
practice this check only found problems very early during the
initialisation rewrite and has found nothing since. This patch removes an
expensive unnecessary check.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Tested-by: Nate Zimmer <nzimmer@sgi.com>
Tested-by: Waiman Long <waiman.long@hp.com>
Tested-by: Daniel J Blueman <daniel@numascale.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Robin Holt <robinmholt@gmail.com>
Cc: Nate Zimmer <nzimmer@sgi.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Waiman Long <waiman.long@hp.com>
Cc: Scott Norton <scott.norton@hp.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Only a subset of struct pages are initialised at the moment. When this
patch is applied kswapd initialise the remaining struct pages in parallel.
This should boot faster by spreading the work to multiple CPUs and
initialising data that is local to the CPU. The user-visible effect on
large machines is that free memory will appear to rapidly increase early
in the lifetime of the system until kswapd reports that all memory is
initialised in the kernel log. Once initialised there should be no other
user-visibile effects.
Signed-off-by: Mel Gorman <mgorman@suse.de>
Tested-by: Nate Zimmer <nzimmer@sgi.com>
Tested-by: Waiman Long <waiman.long@hp.com>
Tested-by: Daniel J Blueman <daniel@numascale.com>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Robin Holt <robinmholt@gmail.com>
Cc: Nate Zimmer <nzimmer@sgi.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Waiman Long <waiman.long@hp.com>
Cc: Scott Norton <scott.norton@hp.com>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mminit_loglevel is only referenced from __init and __meminit functions, so
we can mark it __meminitdata.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vishnu Pratap Singh <vishnu.ps@samsung.com>
Cc: Pintu Kumar <pintu.k@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The only caller of mminit_verify_zonelist is build_all_zonelists_init,
which is annotated with __init, so it should be safe to also mark the
former as __init, saving ~400 bytes of .text.
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Rik van Riel <riel@redhat.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Vishnu Pratap Singh <vishnu.ps@samsung.com>
Cc: Pintu Kumar <pintu.k@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Commit da29bd36224b ("mm/mm_init.c: make creation of the mm_kobj happen
earlier than device_initcall") changed to pure_initcall(mm_sysfs_init).
That's too early: mm_sysfs_init() depends on core_initcall(ksysfs_init)
to have made the kernel_kobj directory "kernel" in which to create "mm".
Make it postcore_initcall(mm_sysfs_init). We could use core_initcall(),
and depend upon Makefile link order kernel/ mm/ fs/ ipc/ security/ ...
as core_initcall(debugfs_init) and core_initcall(securityfs_init) do;
but better not.
Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The use of __initcall is to be eventually replaced by choosing one from
the prioritized groupings laid out in init.h header:
pure_initcall 0
core_initcall 1
postcore_initcall 2
arch_initcall 3
subsys_initcall 4
fs_initcall 5
device_initcall 6
late_initcall 7
In the interim, all __initcall are mapped onto device_initcall, which as
can be seen above, comes quite late in the ordering.
Currently the mm_kobj is created with __initcall in mm_sysfs_init().
This means that any other initcalls that want to reference the mm_kobj
have to be device_initcall (or later), otherwise we will for example,
trip the BUG_ON(!kobj) in sysfs's internal_create_group(). This
unfairly restricts those users; for example something that clearly makes
sense to be an arch_initcall will not be able to choose that.
However, upon examination, it is only this way for historical reasons
(i.e. simply not reprioritized yet). We see that sysfs is ready quite
earlier in init/main.c via:
vfs_caches_init
|_ mnt_init
|_ sysfs_init
well ahead of the processing of the prioritized calls listed above.
So we can recategorize mm_sysfs_init to be a pure_initcall, which in
turn allows any mm_kobj initcall users a wider range (1 --> 7) of
initcall priorities to choose from.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Change the per page last fault tracking to use cpu,pid instead of
nid,pid. This will allow us to try and lookup the alternate task more
easily. Note that even though it is the cpu that is store in the page
flags that the mpol_misplaced decision is still based on the node.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Link: http://lkml.kernel.org/r/1381141781-10992-43-git-send-email-mgorman@suse.de
[ Fixed build failure on 32-bit systems. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Ideally it would be possible to distinguish between NUMA hinting faults that
are private to a task and those that are shared. If treated identically
there is a risk that shared pages bounce between nodes depending on
the order they are referenced by tasks. Ultimately what is desirable is
that task private pages remain local to the task while shared pages are
interleaved between sharing tasks running on different nodes to give good
average performance. This is further complicated by THP as even
applications that partition their data may not be partitioning on a huge
page boundary.
To start with, this patch assumes that multi-threaded or multi-process
applications partition their data and that in general the private accesses
are more important for cpu->memory locality in the general case. Also,
no new infrastructure is required to treat private pages properly but
interleaving for shared pages requires additional infrastructure.
To detect private accesses the pid of the last accessing task is required
but the storage requirements are a high. This patch borrows heavily from
Ingo Molnar's patch "numa, mm, sched: Implement last-CPU+PID hash tracking"
to encode some bits from the last accessing task in the page flags as
well as the node information. Collisions will occur but it is better than
just depending on the node information. Node information is then used to
determine if a page needs to migrate. The PID information is used to detect
private/shared accesses. The preferred NUMA node is selected based on where
the maximum number of approximately private faults were measured. Shared
faults are not taken into consideration for a few reasons.
First, if there are many tasks sharing the page then they'll all move
towards the same node. The node will be compute overloaded and then
scheduled away later only to bounce back again. Alternatively the shared
tasks would just bounce around nodes because the fault information is
effectively noise. Either way accounting for shared faults the same as
private faults can result in lower performance overall.
The second reason is based on a hypothetical workload that has a small
number of very important, heavily accessed private pages but a large shared
array. The shared array would dominate the number of faults and be selected
as a preferred node even though it's the wrong decision.
The third reason is that multiple threads in a process will race each
other to fault the shared page making the fault information unreliable.
Signed-off-by: Mel Gorman <mgorman@suse.de>
[ Fix complication error when !NUMA_BALANCING. ]
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1381141781-10992-30-git-send-email-mgorman@suse.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Currently the per cpu counter's batch size for memory accounting is
configured as twice the number of cpus in the system. However, for
system with very large memory, it is more appropriate to make it
proportional to the memory size per cpu in the system.
For example, for a x86_64 system with 64 cpus and 128 GB of memory, the
batch size is only 2*64 pages (0.5 MB). So any memory accounting
changes of more than 0.5MB will overflow the per cpu counter into the
global counter. Instead, for the new scheme, the batch size is
configured to be 0.4% of the memory/cpu = 8MB (128 GB/64 /256), which is
more inline with the memory size.
I've done a repeated brk test of 800KB (from will-it-scale test suite)
with 80 concurrent processes on a 4 socket Westmere machine with a total
of 40 cores. Without the patch, about 80% of cpu is spent on spin-lock
contention within the vm_committed_as counter. With the patch, there's
a 73x speedup on the benchmark and the lock contention drops off almost
entirely.
[akpm@linux-foundation.org: fix section mismatch]
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Answering the question "how much space remains in the page->flags" is
time-consuming. mminit_loglevel can help answer the question but it
does not take last_nid information into account. This patch corrects it
and while there it corrects the messages related to page flag usage,
pgshifts and node/zone id. When applied the relevant output looks
something like this but will depend on the kernel configuration.
mminit::pageflags_layout_widths Section 0 Node 9 Zone 2 Lastnid 9 Flags 25
mminit::pageflags_layout_shifts Section 19 Node 9 Zone 2 Lastnid 9
mminit::pageflags_layout_pgshifts Section 0 Node 55 Zone 53 Lastnid 44
mminit::pageflags_layout_nodezoneid Node/Zone ID: 64 -> 53
mminit::pageflags_layout_usage location: 64 -> 44 layout 44 -> 25 unused 25 -> 0 page-flags
Signed-off-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The files changed within are only using the EXPORT_SYMBOL
macro variants. They are not using core modular infrastructure
and hence don't need module.h but only the export.h header.
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
mminit_loglevel is now used from mminit_verify_zonelist <- build_all_zonelists <-
1. online_pages <- memory_block_action <- memory_block_change_state <- store_mem_state (sys handler)
2. numa_zonelist_order_handler (proc handler)
so it cannot be annotated __meminit - drop it
fixes following section mismatch warning:
WARNING: vmlinux.o(.text+0x71628): Section mismatch in reference from the function mminit_verify_zonelist() to the variable .meminit.data:mminit_loglevel
The function mminit_verify_zonelist() references
the variable __meminitdata mminit_loglevel.
This is often because mminit_verify_zonelist lacks a __meminitdata
annotation or the annotation of mminit_loglevel is wrong.
Signed-off-by: Marcin Slusarz <marcin.slusarz@gmail.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
gcc-3.2:
mm/mm_init.c:77:1: directives may not be used inside a macro argument
mm/mm_init.c:76:47: unterminated argument list invoking macro "mminit_dprintk"
mm/mm_init.c: In function `mminit_verify_pageflags_layout':
mm/mm_init.c:80: `mminit_dprintk' undeclared (first use in this function)
mm/mm_init.c:80: (Each undeclared identifier is reported only once
mm/mm_init.c:80: for each function it appears in.)
mm/mm_init.c:80: syntax error before numeric constant
Also fix a typo in a comment.
Reported-by: Adrian Bunk <bunk@kernel.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add a kobject to create /sys/kernel/mm when sysfs is mounted. The kobject
will exist regardless. This will allow for the hugepage related sysfs
directories to exist under the mm "subsystem" directory. Add an ABI file
appropriately.
[kosaki.motohiro@jp.fujitsu.com: fix build]
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Towards the end of putting all core mm initialization in mm_init.c, I
plan on putting the creation of a mm kobject in a function in that file.
However, the file is currently only compiled if CONFIG_DEBUG_MEMORY_INIT
is set. Remove this dependency, but put the code under an #ifdef on the
same config option. This should result in no functional changes.
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch prints out the zonelists during boot for manual verification by the
user if the mminit_loglevel is MMINIT_VERIFY or higher.
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Print out information on how the page flags are being used if mminit_loglevel
is MMINIT_VERIFY or higher and unconditionally performs sanity checks on the
flags regardless of loglevel.
When the page flags are updated with section, node and zone information, a
check are made to ensure the values can be retrieved correctly. Finally we
confirm that pfn_to_page and page_to_pfn are the correct inverse functions.
[akpm@linux-foundation.org: fix printk warnings]
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Boot initialisation is very complex, with significant numbers of
architecture-specific routines, hooks and code ordering. While significant
amounts of the initialisation is architecture-independent, it trusts the data
received from the architecture layer. This is a mistake, and has resulted in
a number of difficult-to-diagnose bugs.
This patchset adds some validation and tracing to memory initialisation. It
also introduces a few basic defensive measures. The validation code can be
explicitly disabled for embedded systems.
This patch:
Add additional debugging and verification code for memory initialisation.
Once enabled, the verification checks are always run and when required
additional debugging information may be outputted via a mminit_loglevel=
command-line parameter.
The verification code is placed in a new file mm/mm_init.c. Ideally other mm
initialisation code will be moved here over time.
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
