Various minor optimizations in rb_erase():
- Avoid multiple loading of node->__rb_parent_color when computing parent
and color information (possibly not in close sequence, as there might
be further branches in the algorithm)
- In the 1-child subcase of case 1, copy the __rb_parent_color field from
the erased node to the child instead of recomputing it from the desired
parent and color
- When searching for the erased node's successor, differentiate between
cases 2 and 3 based on whether any left links were followed. This avoids
a condition later down.
- In case 3, keep a pointer to the erased node's right child so we don't
have to refetch it later to adjust its parent.
- In the no-childs subcase of cases 2 and 3, place the rebalance assigment
last so that the compiler can remove the following if(rebalance) test.
Also, added some comments to illustrate cases 2 and 3.
Signed-off-by: Michel Lespinasse <walken@google.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
rbtree: handle 1-child recoloring in rb_erase() instead of rb_erase_color()
An interesting observation for rb_erase() is that when a node has
exactly one child, the node must be black and the child must be red.
An interesting consequence is that removing such a node can be done by
simply replacing it with its child and making the child black,
which we can do efficiently in rb_erase(). __rb_erase_color() then
only needs to handle the no-childs case and can be modified accordingly.
Signed-off-by: Michel Lespinasse <walken@google.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
In rb_erase, move the easy case (node to erase has no more than
1 child) first. I feel the code reads easier that way.
Signed-off-by: Michel Lespinasse <walken@google.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Add __rb_change_child() as an inline helper function to replace code that
would otherwise be duplicated 4 times in the source.
No changes to binary size or speed.
Signed-off-by: Michel Lespinasse <walken@google.com> Reviewed-by: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
rbtree test: fix sparse warning about 64-bit constant
Just a small fix to make sparse happy.
Signed-off-by: Michel Lespinasse <walken@google.com> Reported-by: Fengguang Wu <wfg@linux.intel.com> Acked-by: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw2@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When looking to fetch a node's sibling, we went through a sequence of:
- check if node is the parent's left child
- if it is, then fetch the parent's right child
This can be replaced with:
- fetch the parent's right child as an assumed sibling
- check that node is NOT the fetched child
This avoids fetching the parent's left child when node is actually
that child. Saves a bit on code size, though it doesn't seem to make
a large difference in speed.
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Set comment and indentation style to be consistent with linux coding style
and the rest of the file, as suggested by Peter Zijlstra
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
rbtree: low level optimizations in __rb_erase_color()
In __rb_erase_color(), we often already have pointers to the nodes being
rotated and/or know what their colors must be, so we can generate more
efficient code than the generic __rb_rotate_left() and __rb_rotate_right()
functions.
Also when the current node is red or when flipping the sibling's color,
the parent is already known so we can use the more efficient
rb_set_parent_color() function to set the desired color.
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
rbtree: optimize case selection logic in __rb_erase_color()
In __rb_erase_color(), we have to select one of 3 cases depending on the
color on the 'other' node children. If both children are black, we flip a
few node colors and iterate. Otherwise, we do either one or two tree
rotations, depending on the color of the 'other' child opposite to 'node',
and then we are done.
The corresponding logic had duplicate checks for the color of the 'other'
child opposite to 'node'. It was checking it first to determine if both
children are black, and then to determine how many tree rotations are
required. Rearrange the logic to avoid that extra check.
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
rbtree: adjust node color in __rb_erase_color() only when necessary
In __rb_erase_color(), we were always setting a node to black after
exiting the main loop. And in one case, after fixing up the tree to
satisfy all rbtree invariants, we were setting the current node to root
just to guarantee a loop exit, at which point the root would be set to
black. However this is not necessary, as the root of an rbtree is already
known to be black. The only case where the color flip is required is when
we exit the loop due to the current node being red, and it's easiest to
just do the flip at that point instead of doing it after the loop.
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
rbtree: low level optimizations in rb_insert_color()
- Use the newly introduced rb_set_parent_color() function to flip the color
of nodes whose parent is already known.
- Optimize rb_parent() when the node is known to be red - there is no need
to mask out the color in that case.
- Flipping gparent's color to red requires us to fetch its rb_parent_color
field, so we can reuse it as the parent value for the next loop iteration.
- Do not use __rb_rotate_left() and __rb_rotate_right() to handle tree
rotations: we already have pointers to all relevant nodes, and know their
colors (either because we want to adjust it, or because we've tested it,
or we can deduce it as black due to the node proximity to a known red node).
So we can generate more efficient code by making use of the node pointers
we already have, and setting both the parent and color attributes for
nodes all at once. Also in Case 2, some node attributes don't have to
be set because we know another tree rotation (Case 3) will always follow
and override them.
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
rbtree: adjust root color in rb_insert_color() only when necessary
The root node of an rbtree must always be black. However,
rb_insert_color() only needs to maintain this invariant when it has been
broken - that is, when it exits the loop due to the current (red) node
being the root. In all other cases (exiting after tree rotations, or
exiting due to an existing black parent) the invariant is already
satisfied, so there is no need to adjust the root node color.
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
rbtree: break out of rb_insert_color loop after tree rotation
It is a well known property of rbtrees that insertion never requires more
than two tree rotations. In our implementation, after one loop iteration
identified one or two necessary tree rotations, we would iterate and look
for more. However at that point the node's parent would always be black,
which would cause us to exit the loop.
We can make the code flow more obvious by just adding a break statement
after the tree rotations, where we know we are done. Additionally, in the
cases where two tree rotations are necessary, we don't have to update the
'node' pointer as it wouldn't be used until the next loop iteration, which
we now avoid due to this break statement.
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This small module helps measure the performance of rbtree insert and
erase.
Additionally, we run a few correctness tests to check that the rbtrees
have all desired properties:
- contains the right number of nodes in the order desired,
- never two consecutive red nodes on any path,
- all paths to leaf nodes have the same number of black nodes,
- root node is black
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
David Woodhouse [Fri, 7 Sep 2012 00:23:46 +0000 (10:23 +1000)]
rbtree: fix jffs2 build issue due to renamed __rb_parent_color field
... and clean up the comments to better explain why it's acceptable to
do it this way instead of using rb_erase() "properly".
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
rbtree: move some implementation details from rbtree.h to rbtree.c
rbtree users must use the documented APIs to manipulate the tree
structure. Low-level helpers to manipulate node colors and parenthood are
not part of that API, so move them to lib/rbtree.c
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
rbtree: fix incorrect rbtree node insertion in fs/proc/proc_sysctl.c
The recently added code to use rbtrees in sysctl did not follow the proper
rbtree interface on insertion - it was calling rb_link_node() which
inserts a new node into the binary tree, but missed the call to
rb_insert_color() which properly balances the rbtree and establishes all
expected rbtree invariants.
I found out about this only because faulty commit also used
rb_init_node(), which I am removing within this patchset. But I think
it's an easy mistake to make, and it makes me wonder if we should change
the rbtree API so that insertions would be done with a single rb_insert()
call (even if its implementation could still inline the rb_link_node()
part and call a private __rb_insert_color function to do the rebalancing).
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
After merging the akpm tree, today's linux-next build (x86_64
allmodconfig) failed like this:
net/ceph/osd_client.c: In function 'ceph_osdc_alloc_request':
net/ceph/osd_client.c:216:2: error: implicit declaration of function 'rb_in=
it_node' [-Werror=3Dimplicit-function-declaration]
Caused by commit 753b960e52b7 ("rbtree: empty nodes have no color") from
the akpm tree interacting with commit cd43045c2de6 ("libceph: initialize
rb, list nodes in ceph_osd_request") from the ceph tree.
Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au> Cc: Sage Weil <sage@inktank.com> Reviewed-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Empty nodes have no color. We can make use of this property to simplify
the code emitted by the RB_EMPTY_NODE and RB_CLEAR_NODE macros. Also, we
can get rid of the rb_init_node function which had been introduced by 88d19cf37952 ("timers: Add rb_init_node() to allow for stack allocated rb
nodes") to avoid some issue with the empty node's color not being
initialized.
I'm not sure what the RB_EMPTY_NODE checks in rb_prev() / rb_next() are
doing there, though. axboe introduced them in 10fd48f2376d ("rbtree:
fixed reversed RB_EMPTY_NODE and rb_next/prev"). The way I see it, the
'empty node' abstraction is only used by rbtree users to flag nodes that
they haven't inserted in any rbtree, so asking the predecessor or
successor of such nodes doesn't make any sense.
One final rb_init_node() caller was recently added in sysctl code to
implement faster sysctl name lookups. This code doesn't make use of
RB_EMPTY_NODE at all, and from what I could see it only called
rb_init_node() under the mistaken assumption that such initialization was
required before node insertion.
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: John Stultz <john.stultz@linaro.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
rbtree: reference Documentation/rbtree.txt for usage instructions
I recently started looking at the rbtree code (with an eye towards
improving the augmented rbtree support, but I haven't gotten there yet).
I noticed a lot of possible speed improvements, which I am now proposing
in this patch set.
Patches 1-4 are preparatory: remove internal functions from rbtree.h so
that users won't be tempted to use them instead of the documented APIs,
clean up some incorrect usages I've noticed (in particular, with the
recently added fs/proc/proc_sysctl.c rbtree usage), reference the
documentation so that people have one less excuse to miss it, etc.
Patch 5 is a small module I wrote to check the rbtree performance. It
creates 100 nodes with random keys and repeatedly inserts and erases them
from an rbtree. Additionally, it has code to check for rbtree invariants
after each insert or erase operation.
Patches 6-12 is where the rbtree optimizations are done, and they touch
only that one file, lib/rbtree.c . I am getting good results out of these
- in my small benchmark doing rbtree insertion (including search) and
erase, I'm seeing a 30% runtime reduction on Sandybridge E5, which is more
than I initially thought would be possible. (the results aren't as
impressive on my two other test hosts though, AMD barcelona and Intel
Westmere, where I am seeing 14% runtime reduction only). The code size -
both source (ommiting comments) and compiled - is also shorter after these
changes. However, I do admit that the updated code is more arduous to
read - one big reason for that is the removal of the tree rotation
helpers, which added some overhead but also made it easier to reason about
things locally. Overall, I believe this is an acceptable compromise,
given that this code doesn't get modified very often, and that I have good
tests for it.
Upon Peter's suggestion, I added comments showing the rtree configuration
before every rotation. I think they help; however it's still best to have
a copy of the cormen/leiserson/rivest book when digging into this code.
This patch: reference Documentation/rbtree.txt for usage instructions
include/linux/rbtree.h included some basic usage instructions, while
Documentation/rbtree.txt had some more complete and easier to follow
instructions. Replacing the former with a reference to the latter.
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Acked-by: David Woodhouse <David.Woodhouse@intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Daniel Santos <daniel.santos@pobox.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
d6629859 ("ipc/mqueue: improve performance of send/recv") and ce2d52cc
("ipc/mqueue: add rbtree node caching support") introduced an rbtree of
message priorities, and usage of rb_init_node() to initialize the
corresponding nodes. As it turns out, rb_init_node() is unnecessary here,
as the nodes are fully initialized on insertion by rb_link_node() and the
code doesn't access nodes that aren't inserted on the rbtree.
Removing the rb_init_node() calls as I removed that function during
rbtree API cleanups (the only other use of it was in a place that similarly
didn't require it).
Signed-off-by: Michel Lespinasse <walken@google.com> Acked-by: Doug Ledford <dledford@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This patch is part of the architecture backend for thp on s390. It
disables thp for kvm hosts, because there is no kvm host hugepage support
so far. Existing thp mappings are split by follow_page() with FOLL_SPLIT,
and future thp mappings are prevented by setting VM_NOHUGEPAGE in
mm->def_flags.
This patch is part of the architecture backend for thp on s390. It
provides the pagetable pre-allocation functions
pgtable_trans_huge_deposit() and pgtable_trans_huge_withdraw(). Unlike
other archs, s390 has no struct page * as pgtable_t, but rather a pointer
to the page table. So instead of saving the pagetable pre- allocation
list info inside the struct page, it is being saved within the pagetable
itself.
This patch is part of the architecture backend for thp on s390. It
provides the functions related to thp splitting, including serialization
against gup. Unlike other archs, pmdp_splitting_flush() cannot use a tlb
flushing operation to serialize against gup on s390, because that wouldn't
be stopped by the disabled IRQs. So instead, smp_call_function() is
called with an empty function, which will have the expected effect.
This adds a check to hugepage_madvise(), to refuse MADV_HUGEPAGE if
VM_NOHUGEPAGE is set in mm->def_flags. On s390, the VM_NOHUGEPAGE flag
will be set in mm->def_flags for kvm processes, to prevent any future thp
mappings. In order to also prevent MADV_HUGEPAGE on such an mm,
hugepage_madvise() should check mm->def_flags.
On s390, a valid page table entry must not be changed while it is attached
to any CPU. So instead of pmd_mknotpresent() and set_pmd_at(), an IDTE
operation would be necessary there. This patch introduces the
pmdp_invalidate() function, to allow architecture-specific
implementations.
The thp page table pre-allocation code currently assumes that pgtable_t is
of type "struct page *". This may not be true for all architectures, so
this patch removes that assumption by replacing the functions
prepare_pmd_huge_pte() and get_pmd_huge_pte() with two new functions that
can be defined architecture-specific.
It also removes two VM_BUG_ON checks for page_count() and page_mapcount()
operating on a pgtable_t. Apart from the VM_BUG_ON removal, there will be
no functional change introduced by this patch.
Cleanup patch in preparation for transparent hugepage support on s390.
Adding new architectures to the TRANSPARENT_HUGEPAGE config option can
make the "depends" line rather ugly, like "depends on (X86 || (S390 &&
64BIT)) && MMU".
This patch adds a HAVE_ARCH_TRANSPARENT_HUGEPAGE instead. x86 already has
MMU "def_bool y", so the MMU check is superfluous there and
HAVE_ARCH_TRANSPARENT_HUGEPAGE can be selected in arch/x86/Kconfig.
Signed-off-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Hillf Danton <dhillf@gmail.com> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: fix potential anon_vma locking issue in mprotect()
Fix an anon_vma locking issue in the following situation:
- vma has no anon_vma
- next has an anon_vma
- vma is being shrunk / next is being expanded, due to an mprotect call
We need to take next's anon_vma lock to avoid races with rmap users (such
as page migration) while next is being expanded.
Signed-off-by: Michel Lespinasse <walken@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
thp: merge page pre-alloc in khugepaged_loop into khugepaged_do_scan
There are two pre-alloc operations in these two function, the different is:
- it allows to sleep if page alloc fail in khugepaged_loop
- it exits immediately if page alloc fail in khugepaged_do_scan
Actually, in khugepaged_do_scan, we can allow the pre-alloc to sleep on
the first failure, then the operation in khugepaged_loop can be removed
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
thp: remove wake_up_interruptible in the exit path
Add the check of kthread_should_stop() to the conditions which are used to
wakeup on khugepaged_wait, then kthread_stop is enough to let the thread
exit
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Now, khugepaged creation and cancel are completely serial under the
protection of khugepaged_mutex, it is impossible that many khugepaged
entities are running
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Currently, hugepaged_mutex is used really complexly and hard to
understand, actually, it is just used to serialize start_khugepaged and
khugepaged for these reasons:
- khugepaged_thread is shared between them
- the thp disable path (echo never > transparent_hugepage/enabled) is
nonblocking, so we need to protect khugepaged_thread to get a stable
running state
These can be avoided by:
- use the lock to serialize the thread creation and cancel
- thp disable path can not finised until the thread exits
Then khugepaged_thread is fully controlled by start_khugepaged, khugepaged
will be happy without the lock
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: David Rientjes <rientjes@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Make sure the #endif that terminates the standard #ifndef / #define /
#endif construct gets labeled, and gets positioned at the end of the file
as is normally the case.
Signed-off-by: Michel Lespinasse <walken@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Will Deacon [Fri, 7 Sep 2012 00:23:37 +0000 (10:23 +1000)]
mm: hugetlb: add arch hook for clearing page flags before entering pool
The core page allocator ensures that page flags are zeroed when freeing
pages via free_pages_check. A number of architectures (ARM, PPC, MIPS)
rely on this property to treat new pages as dirty with respect to the data
cache and perform the appropriate flushing before mapping the pages into
userspace.
This can lead to cache synchronisation problems when using hugepages,
since the allocator keeps its own pool of pages above the usual page
allocator and does not reset the page flags when freeing a page into the
pool.
This patch adds a new architecture hook, arch_clear_hugepage_flags, so
that architectures which rely on the page flags being in a particular
state for fresh allocations can adjust the flags accordingly when a page
is freed into the pool.
Signed-off-by: Will Deacon <will.deacon@arm.com> Cc: Michal Hocko <mhocko@suse.cz> Reviewed-by: Michal Hocko <mhocko@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
While registering MMU notifier, new instance of MMU notifier_mm will be
allocated and later free'd if currrent mm_struct's MMU notifier_mm has
been initialized. That causes some overhead. The patch tries to
elominate that.
Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com> Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Avi Kivity <avi@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Sagi Grimberg <sagig@mellanox.co.il> Cc: Haggai Eran <haggaie@mellanox.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: mmu_notifier: have mmu_notifiers use a global SRCU so they may safely schedule
With an RCU based mmu_notifier implementation, any callout to
mmu_notifier_invalidate_range_start(), mmu_notifier_invalidate_range_end()
or mmu_notifier_invalidate_page() would not be allowed to call schedule()
as that could potentially allow a modification to the mmu_notifier
structure while it is currently being used.
Since srcu allocs 4 machine words per instance per cpu, we may end up with
memory exhaustion if we use srcu per mm. So all mms share a global srcu.
Note that during large mmu_notifier activity exit & unregister paths might
hang for longer periods, but it is tolerable for current mmu_notifier
clients.
Signed-off-by: Sagi Grimberg <sagig@mellanox.co.il> Signed-off-by: Andrea Arcangeli <aarcange@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Haggai Eran <haggaie@mellanox.com> Cc: "Paul E. McKenney" <paulmck@us.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: mmu_notifier: fix inconsistent memory between secondary MMU and host
There is a bug in set_pte_at_notify() which always sets the pte to the new
page before releasing the old page in the secondary MMU. At this time,
the process will access on the new page, but the secondary MMU still
access on the old page, the memory is inconsistent between them
The below scenario shows the bug more clearly:
at the beginning: *p = 0, and p is write-protected by KSM or shared with
parent process
CPU 0 CPU 1
write 1 to p to trigger COW,
set_pte_at_notify will be called:
*pte = new_page + W; /* The W bit of pte is set */
*p = 1; /* pte is valid, so no #PF */
return back to secondary MMU, then
the secondary MMU read p, but get:
*p == 0;
/*
* !!!!!!
* the host has already set p to 1, but the secondary
* MMU still get the old value 0
*/
call mmu_notifier_change_pte to release
old page in secondary MMU
We can fix it by release old page first, then set the pte to the new
page.
Note, the new page will be firstly used in secondary MMU before it is
mapped into the page table of the process, but this is safe because it
is protected by the page table lock, there is no race to change the pte
Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> Cc: Avi Kivity <avi@redhat.com> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mempolicy: fix a memory corruption by refcount imbalance in alloc_pages_vma()
cc9a6c87 ("cpuset: mm: reduce large amounts of memory barrier related
damage v3") introduced a potential memory corruption. shmem_alloc_page()
uses a pseudo vma and it has one significant unique combination,
vma->vm_ops=NULL and vma->policy->flags & MPOL_F_SHARED.
get_vma_policy() does NOT increase a policy ref when vma->vm_ops=NULL and
mpol_cond_put() DOES decrease a policy ref when a policy has
MPOL_F_SHARED. Therefore, when a cpuset update race occurs,
alloc_pages_vma() falls in 'goto retry_cpuset' path, decrements the
reference count and frees the policy prematurely.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mempolicy: fix refcount leak in mpol_set_shared_policy()
When shared_policy_replace() fails to allocate new->policy is not freed
correctly by mpol_set_shared_policy(). The problem is that shared
mempolicy code directly call kmem_cache_free() in multiple places where it
is easy to make a mistake.
This patch creates an sp_free wrapper function and uses it. The bug was
introduced pre-git age (IOW, before 2.6.12-rc2).
[mgorman@suse.de: Editted changelog] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
shared_policy_replace() use of sp_alloc() is unsafe. 1) sp_node cannot be
dereferenced if sp->lock is not held and 2) another thread can modify
sp_node between spin_unlock for allocating a new sp node and next
spin_lock. The bug was introduced before 2.6.12-rc2.
Kosaki's original patch for this problem was to allocate an sp node and
policy within shared_policy_replace and initialise it when the lock is
reacquired. I was not keen on this approach because it partially
duplicates sp_alloc(). As the paths were sp->lock is taken are not that
performance critical this patch converts sp->lock to sp->mutex so it can
sleep when calling sp_alloc().
[kosaki.motohiro@jp.fujitsu.com: Original patch] Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Reviewed-by: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The problem is that the structure is being prematurely freed due to a
reference count imbalance. In the following case mbind(addr, len) should
replace the memory policies of both vma1 and vma2 and thus they will
become to share the same mempolicy and the new mempolicy will have the
MPOL_F_SHARED flag.
alloc_pages_vma() uses get_vma_policy() and mpol_cond_put() pair for
maintaining the mempolicy reference count. The current rule is that
get_vma_policy() only increments refcount for shmem VMA and mpol_conf_put()
only decrements refcount if the policy has MPOL_F_SHARED.
In above case, vma1 is not shmem vma and vma->policy has MPOL_F_SHARED!
The reference count will be decreased even though was not increased whenever
alloc_page_vma() is called. This has been broken since commit [52cd3b07:
mempolicy: rework mempolicy Reference Counting] in 2008.
There is another serious bug with the sharing of memory policies. Currently,
mempolicy rebind logic (it is called from cpuset rebinding) ignores a refcount
of mempolicy and override it forcibly. Thus, any mempolicy sharing may cause
mempolicy corruption. The bug was introduced by commit [68860ec1: cpusets:
automatic numa mempolicy rebinding].
Ideally, the shared policy handling would be rewritten to either properly
handle COW of the policy structures or at least reference count MPOL_F_SHARED
based exclusively on information within the policy. However, this patch takes
the easier approach of disabling any policy sharing between VMAs. Each new
range allocated with sp_alloc will allocate a new policy, set the reference
count to 1 and drop the reference count of the old policy. This increases
the memory footprint but is not expected to be a major problem as mbind()
is unlikely to be used for fine-grained ranges. It is also inefficient
because it means we allocate a new policy even in cases where mbind_range()
could use the new_policy passed to it. However, it is more straight-forward
and the change should be invisible to the user.
[mgorman@suse.de: Edited changelog] Reported-by: Dave Jones <davej@redhat.com>, Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Christoph Lameter <cl@linux.com>, Reviewed-by: Christoph Lameter <cl@linux.com> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Revert "mm: mempolicy: Let vma_merge and vma_split handle vma->vm_policy linkages"
05f144a0 ("mm: mempolicy: Let vma_merge and vma_split handle
vma->vm_policy linkages") removed vma->vm_policy updates code but it is
the purpose of mbind_range(). Now, mbind_range() is virtually a no-op and
while it does not allow memory corruption it is not the right fix. This
patch is a revert.
[mgorman@suse.de: Edited changelog] Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Cc: Christoph Lameter <cl@linux.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: compaction: capture a suitable high-order page immediately when it is made available
While compaction is migrating pages to free up large contiguous blocks for
allocation it races with other allocation requests that may steal these
blocks or break them up. This patch alters direct compaction to capture a
suitable free page as soon as it becomes available to reduce this race.
It uses similar logic to split_free_page() to ensure that watermarks are
still obeyed.
Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: vmscan: scale number of pages reclaimed by reclaim/compaction based on failures
If allocation fails after compaction then compaction may be deferred for a
number of allocation attempts. If there are subsequent failures,
compact_defer_shift is increased to defer for longer periods. This patch
uses that information to scale the number of pages reclaimed with
compact_defer_shift until allocations succeed again. The rationale is
that reclaiming the normal number of pages still allowed compaction to
fail and its success depends on the number of pages. If it's failing,
reclaim more pages until it succeeds again.
Note that this is not implying that VM reclaim is not reclaiming enough
pages or that its logic is broken. try_to_free_pages() always asks for
SWAP_CLUSTER_MAX pages to be reclaimed regardless of order and that is
what it does. Direct reclaim stops normally with this check.
if (sc->nr_reclaimed >= sc->nr_to_reclaim)
goto out;
should_continue_reclaim delays when that check is made until a minimum
number of pages for reclaim/compaction are reclaimed. It is possible that
this patch could instead set nr_to_reclaim in try_to_free_pages() and
drive it from there but that's behaves differently and not necessarily for
the better. If driven from do_try_to_free_pages(), it is also possible
that priorities will rise. When they reach DEF_PRIORITY-2, it will also
start stalling and setting pages for immediate reclaim which is more
disruptive than not desirable in this case. That is a more wide-reaching
change that could cause another regression related to THP requests causing
interactive jitter.
Signed-off-by: Mel Gorman <mgorman@suse.de> Acked-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: compaction: update comment in try_to_compact_pages
Allocation success rates have been far lower since 3.4 due to commit fe2c2a10 ("vmscan: reclaim at order 0 when compaction is enabled"). This
commit was introduced for good reasons and it was known in advance that
the success rates would suffer but it was justified on the grounds that
the high allocation success rates were achieved by aggressive reclaim.
Success rates are expected to suffer even more in 3.6 due to commit 7db8889a ("mm: have order > 0 compaction start off where it left") which
testing has shown to severely reduce allocation success rates under load -
to 0% in one case.
This series aims to improve the allocation success rates without
regressing the benefits of commit fe2c2a10. The series is based on latest
mmotm and takes into account the __GFP_NO_KSWAPD flag is going away.
Patch 1 updates a stale comment seeing as I was in the general area.
Patch 2 updates reclaim/compaction to reclaim pages scaled on the number
of recent failures.
Patch 3 captures suitable high-order pages freed by compaction to reduce
races with parallel allocation requests.
Patch 4 fixes the upstream commit [7db8889a: mm: have order > 0 compaction
start off where it left] to enable compaction again
Patch 5 identifies when compacion is taking too long due to contention
and aborts.
From
http://www.csn.ul.ie/~mel/postings/mmtests-20120424/global-dhp__stress-highalloc-performance-ext3/hydra/comparison.html
I know that the allocation success rates in 3.3.6 was 78% in comparison to
36% in in the current akpm tree. With the full series applied, the
success rates are up to around 51% with some variability in the results.
This is not as high a success rate but it does not reclaim excessively
which is a key point.
Note that swap in/out rates remain at 0. In 3.3.6 with 78% success rates
there were 71881 pages swapped out.
Direct pages scanned 70942 122976
Kswapd pages scanned 13663001520122
Kswapd pages reclaimed 13662141484629
Direct pages reclaimed 70936 105716
Kswapd efficiency 99% 97%
Kswapd velocity 1072.550 1182.615
Direct efficiency 99% 85%
Direct velocity 55.690 95.672
The kswapd velocity changes very little as expected. kswapd velocity is
around the 1000 pages/sec mark where as in kernel 3.3.6 with the high
allocation success rates it was 8140 pages/second. Direct velocity is
higher as a result of patch 2 of the series but this is expected and is
acceptable. The direct reclaim and kswapd velocities change very little.
If these get accepted for merging then there is a difficulty in how they
should be handled. 7db8889a ("mm: have order > 0 compaction start off
where it left") is broken but it is already in 3.6-rc1 and needs to be
fixed. However, if just patch 4 from this series is applied then Jim
Schutt's workload is known to break again as his workload also requires
patch 5. While it would be preferred to have all these patches in 3.6 to
improve compaction in general, it would at least be acceptable if just
patches 4 and 5 were merged to 3.6 to fix a known problem without breaking
compaction completely. On the face of it, that would force
__GFP_NO_KSWAPD patches to be merged at the same time but I can do a
version of this series with __GFP_NO_KSWAPD change reverted and then
rebase it on top of this series. That might be best overall because I
note that the __GFP_NO_KSWAPD patch should have removed
deferred_compaction from page_alloc.c but it didn't but fixing that causes
collisions with this series.
This patch:
The comment about order applied when the check was order >
PAGE_ALLOC_COSTLY_ORDER which has not been the case since c5a73c3d ("thp:
use compaction for all allocation orders"). Fixing the comment while I'm
in the general area.
Signed-off-by: Mel Gorman <mgorman@suse.de> Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: Minchan Kim <minchan@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/mmap.c: replace find_vma_prepare() with clearer find_vma_links()
People get confused by find_vma_prepare(), because it doesn't care about
what it returns in its output args, when its callers won't be interested.
Clarify by passing in end-of-range address too, and returning failure if
any existing vma overlaps the new range: instead of returning an ambiguous
vma which most callers then must check. find_vma_links() is a clearer
name.
This does revert 2.6.27's dfe195fb79e88 ("mm: fix uninitialized variables
for find_vma_prepare callers"), but it looks like gcc 4.3.0 was one of
those releases too eager to shout about uninitialized variables: only
copy_vma() warns with 4.5.1 and 4.7.1, which a BUG on error silences.
Robin Dong [Fri, 7 Sep 2012 00:23:09 +0000 (10:23 +1000)]
mm: fix nonuniform page status when writing new file with small buffer
When writing a new file with 2048 bytes buffer, such as write(fd, buffer,
2048), it will call generic_perform_write() twice for every page:
write_begin
mark_page_accessed(page)
write_end
write_begin
mark_page_accessed(page)
write_end
Pages 1-13 will be added to lru-pvecs in write_begin() and will *NOT* be
added to active_list even they have be accessed twice because they are not
PageLRU(page). But when page 14th comes, all pages in lru-pvecs will be
moved to inactive_list (by __lru_cache_add() ) in first write_begin(), now
page 14th *is* PageLRU(page). And after second write_end() only page 14th
will be in active_list.
In Hadoop environment, we do comes to this situation: after writing a
file, we find out that only 14th, 28th, 42th... page are in active_list
and others in inactive_list. Now kswapd works, shrinks the inactive_list,
the file only have 14th, 28th...pages in memory, the readahead request
size will be broken to only 52k (13*4k), system's performance falls
dramatically.
This problem can also replay by below steps (the machine has 8G memory):
1. dd if=/dev/zero of=/test/file.out bs=1024 count=1048576
2. cat another 7.5G file to /dev/null
3. vmtouch -m 1G -v /test/file.out, it will show:
mm: kill vma flag VM_RESERVED and mm->reserved_vm counter
A long time ago, in v2.4, VM_RESERVED kept swapout process off VMA,
currently it lost original meaning but still has some effects:
| effect | alternative flags
-+------------------------+---------------------------------------------
1| account as reserved_vm | VM_IO
2| skip in core dump | VM_IO, VM_DONTDUMP
3| do not merge or expand | VM_IO, VM_DONTEXPAND, VM_HUGETLB, VM_PFNMAP
4| do not mlock | VM_IO, VM_DONTEXPAND, VM_HUGETLB, VM_PFNMAP
This patch removes reserved_vm counter from mm_struct. Seems like nobody
cares about it, it does not exported into userspace directly, it only
reduces total_vm showed in proc.
Thus VM_RESERVED can be replaced with VM_IO or pair VM_DONTEXPAND | VM_DONTDUMP.
remap_pfn_range() and io_remap_pfn_range() set VM_IO|VM_DONTEXPAND|VM_DONTDUMP.
remap_vmalloc_range() set VM_DONTEXPAND | VM_DONTDUMP.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Carsten Otte <cotte@de.ibm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Eric Paris <eparis@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Jason Baron <jbaron@redhat.com> Cc: Kentaro Takeda <takedakn@nttdata.co.jp> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Robert Richter <robert.richter@amd.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Venkatesh Pallipadi <venki@google.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Rename VM_NODUMP into VM_DONTDUMP: this name matches other negative flags:
VM_DONTEXPAND, VM_DONTCOPY. Currently this flag used only for
sys_madvise. The next patch will use it for replacing the outdated flag
VM_RESERVED.
Also forbid madvise(MADV_DODUMP) for special kernel mappings VM_SPECIAL
(VM_IO | VM_DONTEXPAND | VM_RESERVED | VM_PFNMAP)
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Carsten Otte <cotte@de.ibm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Eric Paris <eparis@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Jason Baron <jbaron@redhat.com> Cc: Kentaro Takeda <takedakn@nttdata.co.jp> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Robert Richter <robert.richter@amd.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Venkatesh Pallipadi <venki@google.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: kill vma flag VM_EXECUTABLE and mm->num_exe_file_vmas
Currently the kernel sets mm->exe_file during sys_execve() and then tracks
number of vmas with VM_EXECUTABLE flag in mm->num_exe_file_vmas, as soon
as this counter drops to zero kernel resets mm->exe_file to NULL. Plus it
resets mm->exe_file at last mmput() when mm->mm_users drops to zero.
VMA with VM_EXECUTABLE flag appears after mapping file with flag
MAP_EXECUTABLE, such vmas can appears only at sys_execve() or after vma
splitting, because sys_mmap ignores this flag. Usually binfmt module sets
mm->exe_file and mmaps executable vmas with this file, they hold
mm->exe_file while task is running.
comment from v2.6.25-6245-g925d1c4 ("procfs task exe symlink"),
where all this stuff was introduced:
> The kernel implements readlink of /proc/pid/exe by getting the file from
> the first executable VMA. Then the path to the file is reconstructed and
> reported as the result.
>
> Because of the VMA walk the code is slightly different on nommu systems.
> This patch avoids separate /proc/pid/exe code on nommu systems. Instead of
> walking the VMAs to find the first executable file-backed VMA we store a
> reference to the exec'd file in the mm_struct.
>
> That reference would prevent the filesystem holding the executable file
> from being unmounted even after unmapping the VMAs. So we track the number
> of VM_EXECUTABLE VMAs and drop the new reference when the last one is
> unmapped. This avoids pinning the mounted filesystem.
exe_file's vma accounting is hooked into every file mmap/unmmap and vma
split/merge just to fix some hypothetical pinning fs from umounting by mm,
which already unmapped all its executable files, but still alive.
Seems like currently nobody depends on this behaviour. We can try to
remove this logic and keep mm->exe_file until final mmput().
mm->exe_file is still protected with mm->mmap_sem, because we want to
change it via new sys_prctl(PR_SET_MM_EXE_FILE). Also via this syscall
task can change its mm->exe_file and unpin mountpoint explicitly.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Carsten Otte <cotte@de.ibm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Eric Paris <eparis@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Jason Baron <jbaron@redhat.com> Cc: Kentaro Takeda <takedakn@nttdata.co.jp> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Robert Richter <robert.richter@amd.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Venkatesh Pallipadi <venki@google.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: use mm->exe_file instead of first VM_EXECUTABLE vma->vm_file
Some security modules and oprofile still uses VM_EXECUTABLE for retrieving
a task's executable file. After this patch they will use mm->exe_file
directly. mm->exe_file is protected with mm->mmap_sem, so locking stays
the same.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Acked-by: Chris Metcalf <cmetcalf@tilera.com> [arch/tile] Acked-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> [tomoyo] Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Carsten Otte <cotte@de.ibm.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Eric Paris <eparis@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Acked-by: James Morris <james.l.morris@oracle.com> Cc: Jason Baron <jbaron@redhat.com> Cc: Kentaro Takeda <takedakn@nttdata.co.jp> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Robert Richter <robert.richter@amd.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Venkatesh Pallipadi <venki@google.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Merge VM_INSERTPAGE into VM_MIXEDMAP. VM_MIXEDMAP VMA can mix pure-pfn
ptes, special ptes and normal ptes.
Now copy_page_range() always copies VM_MIXEDMAP VMA on fork like
VM_PFNMAP. If driver populates whole VMA at mmap() it probably not
expects page-faults.
This patch removes special check from vma_wants_writenotify() which
disables pages write tracking for VMA populated via vm_instert_page().
BDI below mapped file should not use dirty-accounting, moreover
do_wp_page() can handle this.
vm_insert_page() still marks vma after first usage. Usually it is called
from f_op->mmap() handler under mm->mmap_sem write-lock, so it able to
change vma->vm_flags. Caller must set VM_MIXEDMAP at mmap time if it
wants to call this function from other places, for example from page-fault
handler.
Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Carsten Otte <cotte@de.ibm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Eric Paris <eparis@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Hugh Dickins <hughd@google.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Jason Baron <jbaron@redhat.com> Cc: Kentaro Takeda <takedakn@nttdata.co.jp> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Robert Richter <robert.richter@amd.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Venkatesh Pallipadi <venki@google.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Replace the generic vma-flag VM_PFN_AT_MMAP with x86-only VM_PAT.
We can toss mapping address from remap_pfn_range() into
track_pfn_vma_new(), and collect all PAT-related logic together in
arch/x86/.
This patch also restores orignal frustration-free is_cow_mapping() check
in remap_pfn_range(), as it was before commit v2.6.28-rc8-88-g3c8bb73
("x86: PAT: store vm_pgoff for all linear_over_vma_region mappings - v3")
is_linear_pfn_mapping() checks can be removed from mm/huge_memory.c,
because it already handled by VM_PFNMAP in VM_NO_THP bit-mask.
[suresh.b.siddha@intel.com: Reset the VM_PAT flag as part of untrack_pfn_vma()] Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Venkatesh Pallipadi <venki@google.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Ingo Molnar <mingo@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Carsten Otte <cotte@de.ibm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Eric Paris <eparis@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Jason Baron <jbaron@redhat.com> Cc: Kentaro Takeda <takedakn@nttdata.co.jp> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Robert Richter <robert.richter@amd.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Cc: Venkatesh Pallipadi <venki@google.com> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
x86, pat: separate the pfn attribute tracking for remap_pfn_range and vm_insert_pfn
With PAT enabled, vm_insert_pfn() looks up the existing pfn memory
attribute and uses it. Expectation is that the driver reserves the memory
attributes for the pfn before calling vm_insert_pfn().
remap_pfn_range() (when called for the whole vma) will setup a new
attribute (based on the prot argument) for the specified pfn range. This
addresses the legacy usage which typically calls remap_pfn_range() with a
desired memory attribute. For ranges smaller than the vma size (which is
typically not the case), remap_pfn_range() will use the existing memory
attribute for the pfn range.
Expose two different API's for these different behaviors.
track_pfn_insert() for tracking the pfn attribute set by vm_insert_pfn()
and track_pfn_remap() for the remap_pfn_range().
This cleanup also prepares the ground for the track/untrack pfn vma routines
to take over the ownership of setting PAT specific vm_flag in the 'vma'.
[khlebnikov@openvz.org: Clear checks in track_pfn_remap()] Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Venkatesh Pallipadi <venki@google.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Nick Piggin <npiggin@kernel.dk> Cc: Ingo Molnar <mingo@redhat.com> Cc: Alexander Viro <viro@zeniv.linux.org.uk> Cc: Carsten Otte <cotte@de.ibm.com> Cc: Chris Metcalf <cmetcalf@tilera.com> Cc: Cyrill Gorcunov <gorcunov@openvz.org> Cc: Eric Paris <eparis@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: James Morris <james.l.morris@oracle.com> Cc: Jason Baron <jbaron@redhat.com> Cc: Kentaro Takeda <takedakn@nttdata.co.jp> Cc: Konstantin Khlebnikov <khlebnikov@openvz.org> Cc: Matt Helsley <matthltc@us.ibm.com> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Robert Richter <robert.richter@amd.com> Cc: Suresh Siddha <suresh.b.siddha@intel.com> Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> Acked-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When transparent huge pages were introduced, memory compaction and swap
storms were an issue, and the kernel had to be careful to not make THP
allocations cause pageout or compaction.
Now that we have working compaction deferral, kswapd is smart enough to
invoke compaction and the quadratic behaviour around isolate_free_pages
has been fixed, it should be safe to remove __GFP_NO_KSWAPD.
[minchan@kernel.org: Comment fix]
[mgorman@suse.de: Avoid direct reclaim for deferred compaction] Cc: Andrea Arcangeli <aarcange@redhat.com> Signed-off-by: Rik van Riel <riel@redhat.com> Signed-off-by: Mel Gorman <mgorman@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
While allocating pages using buddy allocator, the compound page is
probably split up to free pages. Under these circumstances, the compound
page should be destroyed by destroy_compound_page(). However, there is a
duplicate check to judge if the page is compound.
Remove the duplicate check since the compound_order() returns 0 when the
page doesn't have PG_head set in destroy_compound_page(). That is to say,
destroy_compound_page() needn't check PageHead().
Signed-off-by: Gavin Shan <shangw@linux.vnet.ibm.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Acked-by: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
fs: push rcu_barrier() from deactivate_locked_super() to filesystems
There's no reason to call rcu_barrier() on every
deactivate_locked_super(). We only need to make sure that all delayed rcu
free inodes are flushed before we destroy related cache.
Removing rcu_barrier() from deactivate_locked_super() affects some fast
paths. E.g. on my machine exit_group() of a last process in IPC
namespace takes 0.07538s. rcu_barrier() takes 0.05188s of that time.
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
When a file is truncated with truncate()/ftruncate() and then closed,
iversion is not updated. This patch uses ATTR_SIZE flag as an indication
to increment iversion.
Mimi said:
On fput(), i_version is used to detect and flag files that have changed
and need to be re-measured in the IMA measurement policy. When a file
is truncated with truncate()/ftruncate() and then closed, i_version is
not updated. As a result, although the file has changed, it will not be
re-measured and added to the IMA measurement list on subsequent access.
Signed-off-by: Dmitry Kasatkin <dmitry.kasatkin@intel.com> Acked-by: Mimi Zohar <zohar@us.ibm.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stephen Warren [Fri, 7 Sep 2012 00:17:59 +0000 (10:17 +1000)]
block: partition: msdos: provide UUIDs for partitions
The MSDOS/MBR partition table includes a 32-bit unique ID, often referred
to as the NT disk signature. When combined with a partition number within
the table, this can form a unique ID similar in concept to EFI/GPT's
partition UUID. Constructing and recording this value in struct
partition_meta_info allows MSDOS partitions to be referred to on the
kernel command-line using the following syntax:
Stephen Warren [Fri, 7 Sep 2012 00:17:59 +0000 (10:17 +1000)]
init: reduce PARTUUID min length to 1 from 36
Reduce the minimum length for a root=PARTUUID= parameter to be considered
valid from 36 to 1. EFI/GPT partition UUIDs are always exactly 36
characters long, hence the previous limit. However, the next patch will
support DOS/MBR UUIDs too, which have a different, shorter, format.
Instead of validating any particular length, just ensure that at least
some non-empty value was given by the user.
Also, consider a missing UUID value to be a parsing error, in the same
vein as if /PARTNROFF exists and can't be parsed. As such, make both
error cases print a message and disable rootwait. Convert to pr_err while
we're at it.
Signed-off-by: Stephen Warren <swarren@nvidia.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Tejun Heo <tj@kernel.org> Cc: Will Drewry <wad@chromium.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stephen Warren [Fri, 7 Sep 2012 00:17:58 +0000 (10:17 +1000)]
block: store partition_meta_info.uuid as a string
This will allow other types of UUID to be stored here, aside from true
UUIDs. This also simplifies code that uses this field, since it's usually
constructed from a, used as a, or compared to other, strings.
Note: A simplistic approach here would be to set uuid_str[36]=0 whenever a
/PARTNROFF option was found to be present. However, this modifies the
input string, and causes subsequent calls to devt_from_partuuid() not to
see the /PARTNROFF option, which causes different results. In order to
avoid misleading future maintainers, this parameter is marked const.
Signed-off-by: Stephen Warren <swarren@nvidia.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Tejun Heo <tj@kernel.org> Cc: Will Drewry <wad@chromium.org> Cc: Kay Sievers <kay.sievers@vrfy.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Akinobu Mita [Fri, 7 Sep 2012 00:17:58 +0000 (10:17 +1000)]
cciss: use check_signature
Use check_signature() to find a signature in the mmio address.
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Mike Miller <mike.miller@hp.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Stephen M. Cameron <scameron@beardog.cce.hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Akinobu Mita [Fri, 7 Sep 2012 00:17:57 +0000 (10:17 +1000)]
cciss: cleanup bitops usage
- Remove unnecessary correction of bit and address
- Use BITS_TO_LONGS macro to calculate bitmap size
- Use bitmap_zero()
Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Cc: Mike Miller <mike.miller@hp.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Stephen M. Cameron <scameron@beardog.cce.hp.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Dan Carpenter [Fri, 7 Sep 2012 00:17:57 +0000 (10:17 +1000)]
drivers/scsi/ipr.c: remove an unneeded check
"rc" is always zero here, so there is no need to check.
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Acked-by: Brian King <brking@linux.vnet.ibm.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The ACARD driver calls udelay() with a value > 2000, which leads to
to the following compilation error on ARM:
ERROR: "__bad_udelay" [drivers/scsi/atp870u.ko] undefined!
make[1]: *** [__modpost] Error 1
This is because udelay is defined on ARM, roughly speaking, as
The argument to __const_udelay is the number of jiffies to wait divided by
4, but this does not work unless the multiplication does not overflow, and
that is what the build error is designed to prevent. The intended
behavior can be achieved by using mdelay to call udelay multiple times in
a loop.
[jn: adding context] Signed-off-by: Martin Michlmayr <tbm@cyrius.com> Signed-off-by: Jonathan Nieder <jrnieder@gmail.com> Cc: James Bottomley <James.Bottomley@HansenPartnership.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Shaohua Li [Fri, 7 Sep 2012 00:17:56 +0000 (10:17 +1000)]
readahead: fault retry breaks mmap file read random detection
.fault now can retry. The retry can break state machine of .fault. In
filemap_fault, if page is miss, ra->mmap_miss is increased. In the second
try, since the page is in page cache now, ra->mmap_miss is decreased. And
these are done in one fault, so we can't detect random mmap file access.
Add a new flag to indicate .fault is tried once. In the second try, skip
ra->mmap_miss decreasing. The filemap_fault state machine is ok with it.
I only tested x86, didn't test other archs, but looks the change for other
archs is obvious, but who knows :)
Signed-off-by: Shaohua Li <shaohua.li@fusionio.com> Cc: Rik van Riel <riel@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
drivers/thermal/exynos_thermal.c: use devm_* functions
devm_* functions are used to replace kzalloc, request_mem_region, ioremap
and request_irq functions in probe call. With the usage of devm_*
functions explicit freeing and unmapping is not required.
Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org> Signed-off-by: Sachin Kamat <sachin.kamat@samsung.com> Cc: Guenter Roeck <guenter.roeck@ericsson.com> Cc: Len Brown <lenb@kernel.org> Cc: "Brown, Len" <len.brown@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
ARM: exynos: add thermal sensor driver platform data support
Add necessary default platform data support needed for TMU driver. This
dt/non-dt values are tested for origen exynos4210 and smdk exynos5250
platforms.
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org> Cc: Donggeun Kim <dg77.kim@samsung.com> Acked-by: Guenter Roeck <guenter.roeck@ericsson.com> Cc: SangWook Ju <sw.ju@samsung.com> Cc: Durgadoss <durgadoss.r@intel.com> Cc: Len Brown <lenb@kernel.org> Cc: Jean Delvare <khali@linux-fr.org> Cc: Kyungmin Park <kmpark@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
thermal: exynos: register the tmu sensor with the kernel thermal layer
This code added creates a link between temperature sensors, linux thermal
framework and cooling devices for samsung exynos platform. This layer
monitors the temperature from the sensor and informs the generic thermal
layer to take the necessary cooling action.
[akpm@linux-foundation.org: fix comment layout] Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org> Cc: Donggeun Kim <dg77.kim@samsung.com> Acked-by: Guenter Roeck <guenter.roeck@ericsson.com> Cc: SangWook Ju <sw.ju@samsung.com> Cc: Durgadoss <durgadoss.r@intel.com> Cc: Len Brown <lenb@kernel.org> Cc: Jean Delvare <khali@linux-fr.org> Cc: Kyungmin Park <kmpark@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
thermal: exynos5: add exynos5 thermal sensor driver support
Insert exynos5 TMU sensor changes into the thermal driver. Some exynos4
changes are made generic for exynos series.
[akpm@linux-foundation.org: fix comment layout] Signed-off-by: SangWook Ju <sw.ju@samsung.com> Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org> Cc: Donggeun Kim <dg77.kim@samsung.com> Acked-by: Guenter Roeck <guenter.roeck@ericsson.com> Cc: Durgadoss <durgadoss.r@intel.com> Cc: Len Brown <lenb@kernel.org> Cc: Jean Delvare <khali@linux-fr.org> Cc: Kyungmin Park <kmpark@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
hwmon: exynos4: move thermal sensor driver to driver/thermal directory
This movement is needed because the hwmon entries and corresponding sysfs
interface is a duplicate of utilities already provided by
driver/thermal/thermal_sys.c. The goal is to place it in thermal folder
and add necessary functions to use the in-kernel thermal interfaces.
Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org> Signed-off-by: Donggeun Kim <dg77.kim@samsung.com> Acked-by: Guenter Roeck <guenter.roeck@ericsson.com> Cc: SangWook Ju <sw.ju@samsung.com> Cc: Durgadoss <durgadoss.r@intel.com> Cc: Len Brown <lenb@kernel.org> Cc: Jean Delvare <khali@linux-fr.org> Cc: Kyungmin Park <kmpark@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This patchset introduces a new generic cooling device based on cpufreq
that can be used on non-ACPI platforms. As a proof of concept, we have
drivers for the following platforms using this mechanism now:
* Samsung Exynos (Exynos4 and Exynos5) in the current patchset.
* TI OMAP (git://git.linaro.org/people/amitdanielk/linux.git omap4460_thermal)
* Freescale i.MX (git://git.linaro.org/people/amitdanielk/linux.git imx6q_thermal)
There is a small change in cpufreq cooling registration APIs, so a minor
change is needed for OMAP and Freescale platforms.
Brief Description:
1) The generic cooling devices code is placed inside driver/thermal/*
as placing inside acpi folder will need un-necessary enabling of acpi
code. This codes is architecture independent.
2) This patchset adds generic cpu cooling low level implementation
through frequency clipping. In future, other cpu related cooling
devices may be added here. An ACPI version of this already exists
(drivers/acpi/processor_thermal.c) . But this will be useful for
platforms like ARM using the generic thermal interface along with the
generic cpu cooling devices. The cooling device registration API's
return cooling device pointers which can be easily binded with the
thermal zone trip points. The important APIs exposed are,
a) struct thermal_cooling_device *cpufreq_cooling_register(
struct freq_clip_table *tab_ptr, unsigned int tab_size)
b) void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
3) Samsung exynos platform thermal implementation is done using the
generic cpu cooling APIs and the new trip type. The temperature sensor
driver present in the hwmon folder(registered as hwmon driver) is moved
to thermal folder and registered as a thermal driver.
A simple data/control flow diagrams is shown below,
Core Linux thermal <-----> Exynos thermal interface <----- Temperature Sensor
| |
\|/ |
Cpufreq cooling device <---------------
TODO:
*Will send the DT enablement patches later after the driver is merged.
This patch:
Add support for generic cpu thermal cooling low level implementations
using frequency scaling up/down based on the registration parameters.
Different cpu related cooling devices can be registered by the user and
the binding of these cooling devices to the corresponding trip points can
be easily done as the registration APIs return the cooling device pointer.
The user of these APIs are responsible for passing clipping frequency .
The drivers can also register to recieve notification about any cooling
action called.
[akpm@linux-foundation.org: fix comment layout] Signed-off-by: Amit Daniel Kachhap <amit.kachhap@linaro.org> Cc: Donggeun Kim <dg77.kim@samsung.com> Cc: Guenter Roeck <guenter.roeck@ericsson.com> Cc: SangWook Ju <sw.ju@samsung.com> Cc: Durgadoss <durgadoss.r@intel.com> Cc: Len Brown <lenb@kernel.org> Cc: Jean Delvare <khali@linux-fr.org> Cc: Kyungmin Park <kmpark@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
The block control group, infiniband, xfs, crypto, 802.11, netfilter.
Nothing quite so fundamental as fs/namespace.c but definitely in
multiplatform-code that should work, and is already broken on those
architecutres.
Looking at the implementation of atomic64_add_return in lib/atomic64.c the
code looks as efficient as these kinds of things get.
Which leads me to the conclusion that we need atomic64 support on all
architectures.
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Yoshinori Sato <ysato@users.sourceforge.jp> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
projects / karo-tx-linux.git / log