Don't uncharge when do_swap_page's call to do_wp_page fails: the page which
was charged for is there in the pagetable, and will be correctly uncharged
when that area is unmapped - it was only its COWing which failed.
And while we're here, remove earlier XXX comment: yes, OR in do_wp_page's
return value (maybe VM_FAULT_WRITE) with do_swap_page's there; but if it
fails, mask out success bits, which might confuse some arches e.g. sparc.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: David Rientjes <rientjes@google.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Hirokazu Takahashi <taka@valinux.co.jp>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86:
x86: cpa, fix out of date comment
KVM is not seen under X86 config with latest git (32 bit compile)
x86: cpa: ensure page alignment
x86: include proper prototypes for rodata_test
x86: fix gart_iommu_init()
x86: EFI set_memory_x()/set_memory_uc() fixes
x86: make dump_pagetable() static
x86: fix "BUG: sleeping function called from invalid context" in print_vma_addr()
d_path() is used on a <dentry,vfsmount> pair. Lets use a struct path to
reflect this.
[akpm@linux-foundation.org: fix build in mm/memory.c]
Signed-off-by: Jan Blunck <jblunck@suse.de>
Acked-by: Bryan Wu <bryan.wu@analog.com>
Acked-by: Christoph Hellwig <hch@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Cc: Neil Brown <neilb@suse.de>
Cc: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jiri Kosina reported the following deadlock scenario with
show_unhandled_signals enabled:
[ 68.379022] gnome-settings-[2941] trap int3 ip:3d2c840f34
sp:7fff36f5d100 error:0<3>BUG: sleeping function called from invalid
context at kernel/rwsem.c:21
[ 68.379039] in_atomic():1, irqs_disabled():0
[ 68.379044] no locks held by gnome-settings-/2941.
[ 68.379050] Pid: 2941, comm: gnome-settings- Not tainted 2.6.25-rc1 #30
[ 68.379054]
[ 68.379056] Call Trace:
[ 68.379061] <#DB> [<ffffffff81064883>] ? __debug_show_held_locks+0x13/0x30
[ 68.379109] [<ffffffff81036765>] __might_sleep+0xe5/0x110
[ 68.379123] [<ffffffff812f2240>] down_read+0x20/0x70
[ 68.379137] [<ffffffff8109cdca>] print_vma_addr+0x3a/0x110
[ 68.379152] [<ffffffff8100f435>] do_trap+0xf5/0x170
[ 68.379168] [<ffffffff8100f52b>] do_int3+0x7b/0xe0
[ 68.379180] [<ffffffff812f4a6f>] int3+0x9f/0xd0
[ 68.379203] <<EOE>>
[ 68.379229] in libglib-2.0.so.0.1505.0[3d2c800000+dc000]
and tracked it down to:
commit 03252919b7
Author: Andi Kleen <ak@suse.de>
Date: Wed Jan 30 13:33:18 2008 +0100
x86: print which shared library/executable faulted in segfault etc. messages
the problem is that we call down_read() from an atomic context.
Solve this by returning from print_vma_addr() if the preempt count is
elevated. Update preempt_conditional_sti / preempt_conditional_cli to
unconditionally lift the preempt count even on !CONFIG_PREEMPT.
Reported-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
So I spent a while pounding my head against my monitor trying to figure
out the vmsplice() vulnerability - how could a failure to check for
*read* access turn into a root exploit? It turns out that it's a buffer
overflow problem which is made easy by the way get_user_pages() is
coded.
In particular, "len" is a signed int, and it is only checked at the
*end* of a do {} while() loop. So, if it is passed in as zero, the loop
will execute once and decrement len to -1. At that point, the loop will
proceed until the next invalid address is found; in the process, it will
likely overflow the pages array passed in to get_user_pages().
I think that, if get_user_pages() has been asked to grab zero pages,
that's what it should do. Thus this patch; it is, among other things,
enough to block the (already fixed) root exploit and any others which
might be lurking in similar code. I also think that the number of pages
should be unsigned, but changing the prototype of this function probably
requires some more careful review.
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Background: I've implemented 1K/2K page tables for s390. These sub-page
page tables are required to properly support the s390 virtualization
instruction with KVM. The SIE instruction requires that the page tables
have 256 page table entries (pte) followed by 256 page status table entries
(pgste). The pgstes are only required if the process is using the SIE
instruction. The pgstes are updated by the hardware and by the hypervisor
for a number of reasons, one of them is dirty and reference bit tracking.
To avoid wasting memory the standard pte table allocation should return
1K/2K (31/64 bit) and 2K/4K if the process is using SIE.
Problem: Page size on s390 is 4K, page table size is 1K or 2K. That means
the s390 version for pte_alloc_one cannot return a pointer to a struct
page. Trouble is that with the CONFIG_HIGHPTE feature on x86 pte_alloc_one
cannot return a pointer to a pte either, since that would require more than
32 bit for the return value of pte_alloc_one (and the pte * would not be
accessible since its not kmapped).
Solution: The only solution I found to this dilemma is a new typedef: a
pgtable_t. For s390 pgtable_t will be a (pte *) - to be introduced with a
later patch. For everybody else it will be a (struct page *). The
additional problem with the initialization of the ptl lock and the
NR_PAGETABLE accounting is solved with a constructor pgtable_page_ctor and
a destructor pgtable_page_dtor. The page table allocation and free
functions need to call these two whenever a page table page is allocated or
freed. pmd_populate will get a pgtable_t instead of a struct page pointer.
To get the pgtable_t back from a pmd entry that has been installed with
pmd_populate a new function pmd_pgtable is added. It replaces the pmd_page
call in free_pte_range and apply_to_pte_range.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nick Piggin pointed out that swap cache and page cache addition routines
could be called from non GFP_KERNEL contexts. This patch makes the
charging routine aware of the gfp context. Charging might fail if the
cgroup is over it's limit, in which case a suitable error is returned.
This patch was tested on a Powerpc box. I am still looking at being able
to test the path, through which allocations happen in non GFP_KERNEL
contexts.
[kamezawa.hiroyu@jp.fujitsu.com: problem with ZONE_MOVABLE]
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: David Rientjes <rientjes@google.com>
Cc: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add the accounting hooks. The accounting is carried out for RSS and Page
Cache (unmapped) pages. There is now a common limit and accounting for both.
The RSS accounting is accounted at page_add_*_rmap() and page_remove_rmap()
time. Page cache is accounted at add_to_page_cache(),
__delete_from_page_cache(). Swap cache is also accounted for.
Each page's page_cgroup is protected with the last bit of the
page_cgroup pointer, this makes handling of race conditions involving
simultaneous mappings of a page easier. A reference count is kept in the
page_cgroup to deal with cases where a page might be unmapped from the RSS
of all tasks, but still lives in the page cache.
Credits go to Vaidyanathan Srinivasan for helping with reference counting work
of the page cgroup. Almost all of the page cache accounting code has help
from Vaidyanathan Srinivasan.
[hugh@veritas.com: fix swapoff breakage]
[akpm@linux-foundation.org: fix locking]
Signed-off-by: Vaidyanathan Srinivasan <svaidy@linux.vnet.ibm.com>
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Pavel Emelianov <xemul@openvz.org>
Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Kirill Korotaev <dev@sw.ru>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: David Rientjes <rientjes@google.com>
Cc: <Valdis.Kletnieks@vt.edu>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
based on similar patch from: Pavel Machek <pavel@ucw.cz>
Introduce CONFIG_COMPAT_BRK. If disabled then the kernel is free
(but not obliged to) randomize the brk area.
Heap randomization breaks ancient binaries, so we keep COMPAT_BRK
enabled by default.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
After running SetPageUptodate, preceeding stores to the page contents to
actually bring it uptodate may not be ordered with the store to set the
page uptodate.
Therefore, another CPU which checks PageUptodate is true, then reads the
page contents can get stale data.
Fix this by having an smp_wmb before SetPageUptodate, and smp_rmb after
PageUptodate.
Many places that test PageUptodate, do so with the page locked, and this
would be enough to ensure memory ordering in those places if
SetPageUptodate were only called while the page is locked. Unfortunately
that is not always the case for some filesystems, but it could be an idea
for the future.
Also bring the handling of anonymous page uptodateness in line with that of
file backed page management, by marking anon pages as uptodate when they
_are_ uptodate, rather than when our implementation requires that they be
marked as such. Doing allows us to get rid of the smp_wmb's in the page
copying functions, which were especially added for anonymous pages for an
analogous memory ordering problem. Both file and anonymous pages are
handled with the same barriers.
FAQ:
Q. Why not do this in flush_dcache_page?
A. Firstly, flush_dcache_page handles only one side (the smb side) of the
ordering protocol; we'd still need smp_rmb somewhere. Secondly, hiding away
memory barriers in a completely unrelated function is nasty; at least in the
PageUptodate macros, they are located together with (half) the operations
involved in the ordering. Thirdly, the smp_wmb is only required when first
bringing the page uptodate, wheras flush_dcache_page should be called each time
it is written to through the kernel mapping. It is logically the wrong place to
put it.
Q. Why does this increase my text size / reduce my performance / etc.
A. Because it is adding the necessary instructions to eliminate the data-race.
Q. Can it be improved?
A. Yes, eg. if you were to create a rule that all SetPageUptodate operations
run under the page lock, we could avoid the smp_rmb places where PageUptodate
is queried under the page lock. Requires audit of all filesystems and at least
some would need reworking. That's great you're interested, I'm eagerly awaiting
your patches.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
fastcall is always defined to be empty, remove it
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(with Martin Schwidefsky <schwidefsky@de.ibm.com>)
The pgd/pud/pmd/pte page table allocation functions get a mm_struct pointer as
first argument. The free functions do not get the mm_struct argument. This
is 1) asymmetrical and 2) to do mm related page table allocations the mm
argument is needed on the free function as well.
[kamalesh@linux.vnet.ibm.com: i386 fix]
[akpm@linux-foundation.org: coding-syle fixes]
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: Kamalesh Babulal <kamalesh@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
vmtruncate is a twisted maze of gotos, this patch cleans it up to have a
proper if else for the two major cases of extending and truncating truncate
and thus makes it a lot more readable while keeping exactly the same
functinality.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Building in a filesystem on a loop device on a tmpfs file can hang when
swapping, the loop thread caught in that infamous throttle_vm_writeout.
In theory this is a long standing problem, which I've either never seen in
practice, or long ago suppressed the recollection, after discounting my load
and my tmpfs size as unrealistically high. But now, with the new aops, it has
become easy to hang on one machine.
Loop used to grab_cache_page before the old prepare_write to tmpfs, which
seems to have been enough to free up some memory for any swapin needed; but
the new write_begin lets tmpfs find or allocate the page (much nicer, since
grab_cache_page missed tmpfs pages in swapcache).
When allocating a fresh page, tmpfs respects loop's mapping_gfp_mask, which
has __GFP_IO|__GFP_FS stripped off, and throttle_vm_writeout is designed to
break out when __GFP_IO or GFP_FS is unset; but when tmfps swaps in,
read_swap_cache_async allocates with GFP_HIGHUSER_MOVABLE regardless of the
mapping_gfp_mask - hence the hang.
So, pass gfp_mask down the line from shmem_getpage to shmem_swapin to
swapin_readahead to read_swap_cache_async to add_to_swap_cache.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
swapin_readahead has never sat well in mm/memory.c: move it to mm/swap_state.c
beside its kindred read_swap_cache_async. Why were its args in a different
order? rearrange them. And since it was always followed by a
read_swap_cache_async of the target page, fold that in and return struct
page*. Then CONFIG_SWAP=n no longer needs valid_swaphandles and
read_swap_cache_async stubs.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
For three years swapin_readahead has been cluttered with fanciful CONFIG_NUMA
code, advancing addr, and stepping on to the next vma at the boundary, to line
up the mempolicy for each page allocation.
It _might_ be a good idea to allocate swap more according to vma layout; but
the fact is, that's not how we do it at all, 2.6 even less than 2.4: swap is
allocated as needed for pages as they sink to the bottom of the inactive LRUs.
Sometimes that may match vma layout, but not so often that it's worth going
to these misleading vma->vm_next lengths: rip all that out.
Originally I intended to retain the incrementation of addr, but correct its
initial value: valid_swaphandles generally supplies an offset below the target
addr (this is readaround rather than readahead), but addr has not been
adjusted accordingly, so in the interleave case it has usually been allocating
the target page from the "wrong" node (though that may not matter very much).
But look at the equivalent shmem_swapin code: either by oversight or by
design, though it has all the apparatus for choosing a new mempolicy per page,
it uses the same idx throughout, choosing the same mempolicy and interleave
node for each page of the cluster.
Which is actually a much better strategy: each node has its own LRUs and its
own kswapd, so if you're betting on any particular relationship between swap
and node, the best bet is that nearby swap entries belong to pages from the
same node - even when the mempolicy of the target page is to interleave. And
examining a map of nodes corresponding to swap entries on a numa=fake system
bears this out. (We could later tweak swap allocation to make it even more
likely, but this patch is merely about removing cruft.)
So, neither adjust nor increment addr in swapin_readahead, and then
shmem_swapin can use it too; the pseudo-vma to pass policy need only be set up
once per cluster, and so few fields of pvma are used, let's skip the memset -
from shmem_alloc_page also.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <ak@suse.de>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We already have page table manipulation for vmalloc in vmalloc.c. Move the
vmalloc_to_page() function there as well.
Move the definitions for vmalloc related functions in mm.h to a newly created
section. A better place would be vmalloc.h but mm.h is basic and may depend
on these functions. An alternative would be to include vmalloc.h in mm.h
(like done for vmstat.h).
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
They now look like:
hal-resmgr[13791]: segfault at 3c rip 2b9c8caec182 rsp 7fff1e825d30 error 4 in libacl.so.1.1.0[2b9c8caea000+6000]
This makes it easier to pinpoint bugs to specific libraries.
And printing the offset into a mapping also always allows to find the
correct fault point in a library even with randomized mappings. Previously
there was no way to actually find the correct code address inside
the randomized mapping.
Relies on earlier patch to shorten the printk formats.
They are often now longer than 80 characters, but I think that's worth it.
[includes fix from Eric Dumazet to check d_path error value]
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
The break_lock data structure and code for spinlocks is quite nasty.
Not only does it double the size of a spinlock but it changes locking to
a potentially less optimal trylock.
Put all of that under CONFIG_GENERIC_LOCKBREAK, and introduce a
__raw_spin_is_contended that uses the lock data itself to determine whether
there are waiters on the lock, to be used if CONFIG_GENERIC_LOCKBREAK is
not set.
Rename need_lockbreak to spin_needbreak, make it use spin_is_contended to
decouple it from the spinlock implementation, and make it typesafe (rwlocks
do not have any need_lockbreak sites -- why do they even get bloated up
with that break_lock then?).
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Update ctime and mtime for memory-mapped files at a write access on
a present, read-only PTE, as well as at a write on a non-present PTE.
Signed-off-by: Anton Salikhmetov <salikhmetov@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch puts #ifdef CONFIG_DEBUG_VM around a check in vm_normal_page
that verifies that a pfn is valid. This patch increases performance of the
page fault microbenchmark in lmbench by 13% and overall dbench performance
by 7% on s390x. pfn_valid() is an expensive operation on s390 that needs a
high double digit amount of CPU cycles. Nick Piggin suggested that
pfn_valid() involves an array lookup on systems with sparsemem, and
therefore is an expensive operation there too.
The check looks like a clear debug thing to me, it should never trigger on
regular kernels. And if a pte is created for an invalid pfn, we'll find
out once the memory gets accessed later on anyway. Please consider
inclusion of this patch into mm.
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
When calling get_user_pages(), a write flag is passed in by the caller to
indicate if write access is required on the faulted-in pages. Currently,
follow_hugetlb_page() ignores this flag and always faults pages for
read-only access. This can cause data corruption because a device driver
that calls get_user_pages() with write set will not expect COW faults to
occur on the returned pages.
This patch passes the write flag down to follow_hugetlb_page() and makes
sure hugetlb_fault() is called with the right write_access parameter.
[ezk@cs.sunysb.edu: build fix]
Signed-off-by: Adam Litke <agl@us.ibm.com>
Reviewed-by: Ken Chen <kenchen@google.com>
Cc: David Gibson <hermes@gibson.dropbear.id.au>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Erez Zadok <ezk@cs.sunysb.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch removes the no longer used EXPORT_SYMBOL_GPL(access_process_vm).
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
