We can use the global ZVC counters to establish the exact size of the LRU
and the free pages. This allows a more accurate determination of the dirty
ratio.
This patch will fix the broken ratio calculations if large amounts of
memory are allocated to huge pags or other consumers that do not put the
pages on to the LRU.
Notes:
- I did not add NR_SLAB_RECLAIMABLE to the calculation of the
dirtyable pages. Those may be reclaimable but they are at this
point not dirtyable. If NR_SLAB_RECLAIMABLE would be considered
then a huge number of reclaimable pages would stop writeback
from occurring.
- This patch used to be in mm as the last one in a series of patches.
It was removed when Linus updated the treatment of highmem because
there was a conflict. I updated the patch to follow Linus' approach.
This patch is neede to fulfill the claims made in the beginning of the
patchset that is now in Linus' tree.
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>
The nr_cpu_ids value is currently only calculated in smp_init. However, it
may be needed before (SLUB needs it on kmem_cache_init!) and other kernel
components may also want to allocate dynamically sized per cpu array before
smp_init. So move the determination of possible cpus into sched_init()
where we already loop over all possible cpus early in boot.
Also initialize both nr_node_ids and nr_cpu_ids with the highest value they
could take. If we have accidental users before these values are determined
then the current valud of 0 may cause too small per cpu and per node arrays
to be allocated. If it is set to the maximum possible then we only waste
some memory for early boot users.
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>
Add a new mm function apply_to_page_range() which applies a given function to
every pte in a given virtual address range in a given mm structure. This is a
generic alternative to cut-and-pasting the Linux idiomatic pagetable walking
code in every place that a sequence of PTEs must be accessed.
Although this interface is intended to be useful in a wide range of
situations, it is currently used specifically by several Xen subsystems, for
example: to ensure that pagetables have been allocated for a virtual address
range, and to construct batched special pagetable update requests to map I/O
memory (in ioremap()).
[akpm@linux-foundation.org: fix warning, unpleasantly]
Signed-off-by: Ian Pratt <ian.pratt@xensource.com>
Signed-off-by: Christian Limpach <Christian.Limpach@cl.cam.ac.uk>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Matt Mackall <mpm@waste.org>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This introduce krealloc() that reallocates memory while keeping the contents
unchanged. The allocator avoids reallocation if the new size fits the
currently used cache. I also added a simple non-optimized version for
mm/slob.c for compatibility.
[akpm@linux-foundation.org: fix warnings]
Acked-by: Josef Sipek <jsipek@fsl.cs.sunysb.edu>
Acked-by: Matt Mackall <mpm@selenic.com>
Acked-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Xen and VMI both have special requirements when mapping a highmem pte
page into the kernel address space. These can be dealt with by adding
a new kmap_atomic_pte() function for mapping highptes, and hooking it
into the paravirt_ops infrastructure.
Xen specifically wants to map the pte page RO, so this patch exposes a
helper function, kmap_atomic_prot, which maps the page with the
specified page protections.
This also adds a kmap_flush_unused() function to clear out the cached
kmap mappings. Xen needs this to clear out any potential stray RW
mappings of pages which will become part of a pagetable.
[ Zach - vmi.c will need some attention after this patch. It wasn't
immediately obvious to me what needs to be done. ]
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: Zachary Amsden <zach@vmware.com>
Add hooks to allow a paravirt implementation to track the lifetime of
an mm. Paravirtualization requires three hooks, but only two are
needed in common code. They are:
arch_dup_mmap, which is called when a new mmap is created at fork
arch_exit_mmap, which is called when the last process reference to an
mm is dropped, which typically happens on exit and exec.
The third hook is activate_mm, which is called from the arch-specific
activate_mm() macro/function, and so doesn't need stub versions for
other architectures. It's called when an mm is first used.
Signed-off-by: Jeremy Fitzhardinge <jeremy@xensource.com>
Signed-off-by: Andi Kleen <ak@suse.de>
Cc: linux-arch@vger.kernel.org
Cc: James Bottomley <James.Bottomley@SteelEye.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Ugly ifdef, but should handle all 64bit platforms that have suitable
zones. On some like Altix it's probably impossible without IOMMU
use to get memory <4GB this way, but they have to live with that.
Signed-off-by: Andi Kleen <ak@suse.de>
Do this really early in the 2.6.22-rc series, so that we'll get
feedback. And don't change by half measures. Just cut the default
dirty limit to a quarter of what it was, and see if anybody even
notices.
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The page_test_and_clear_dirty primitive really consists of two
operations, page_test_dirty and the page_clear_dirty. The combination
of the two is not an atomic operation, so it makes more sense to have
two separate operations instead of one.
In addition to the improved readability of the s390 version of
SetPageUptodate, it now avoids the page_test_dirty operation which is
an insert-storage-key-extended (iske) instruction which is an expensive
operation.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
* 'for-linus' of git://git390.osdl.marist.edu/pub/scm/linux-2.6:
[S390] cio: Fix handling of interrupt for csch().
[S390] page_mkclean data corruption.
Mention the slab name when listing corrupt objects. Although the function
that released the memory is mentioned, that is frequently ambiguous as such
functions often release several pieces of memory.
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The git commit c2fda5fed8 which
added the page_test_and_clear_dirty call to page_mkclean and the
git commit 7658cc2892 which fixes
the "nasty and subtle race in shared mmap'ed page writeback"
problem in clear_page_dirty_for_io cause data corruption on s390.
The effect of the two changes is that for every call to
clear_page_dirty_for_io a page_test_and_clear_dirty is done. If
the per page dirty bit is set set_page_dirty is called. Strangly
clear_page_dirty_for_io is called for not-uptodate pages, e.g.
over this call-chain:
[<000000000007c0f2>] clear_page_dirty_for_io+0x12a/0x130
[<000000000007c494>] generic_writepages+0x258/0x3e0
[<000000000007c692>] do_writepages+0x76/0x7c
[<00000000000c7a26>] __writeback_single_inode+0xba/0x3e4
[<00000000000c831a>] sync_sb_inodes+0x23e/0x398
[<00000000000c8802>] writeback_inodes+0x12e/0x140
[<000000000007b9ee>] wb_kupdate+0xd2/0x178
[<000000000007cca2>] pdflush+0x162/0x23c
The bad news now is that page_test_and_clear_dirty might claim
that a not-uptodate page is dirty since SetPageUptodate which
resets the per page dirty bit has not yet been called. The page
writeback that follows clobbers the data on disk.
The simplest solution to this problem is to move the call to
page_test_and_clear_dirty under the "if (page_mapped(page))".
If a file backed page is mapped it is uptodate.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Fix the bug, that reading into xip mapping from /dev/zero fills the user
page table with ZERO_PAGE() entries. Later on, xip cannot tell which pages
have been ZERO_PAGE() filled by access to a sparse mapping, and which ones
origin from /dev/zero. It will unmap ZERO_PAGE from all mappings when
filling the sparse hole with data. xip does now use its own zeroed page
for its sparse mappings. Please apply.
Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
sys_madvise has down_write of mmap_sem, then madvise_remove calls
vmtruncate_range which takes i_mutex and i_alloc_sem: no, we can easily devise
deadlocks from that ordering.
madvise_remove drop mmap_sem while calling vmtruncate_range: luckily, since
madvise_remove doesn't split or merge vmas, it's easy to handle this case with
a NULL prev, without restructuring sys_madvise. (Though sad to retake
mmap_sem when it's unlikely to be needed, and certainly down_read is
sufficient for MADV_REMOVE, unlike the other madvices.)
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
shmem_truncate_range has its own truncate_inode_pages_range, to free any pages
racily instantiated while it was in progress: a SHMEM_PAGEIN flag is set when
this might have happened. But holepunching gets no chance to clear that flag
at the start of vmtruncate_range, so it's always set (unless a truncate came
just before), so holepunch almost always does this second
truncate_inode_pages_range.
shmem holepunch has unlikely swap<->file races hereabouts whatever we do
(without a fuller rework than is fit for this release): I was going to skip
the second truncate in the punch_hole case, but Miklos points out that would
make holepunch correctness more vulnerable to swapoff. So keep the second
truncate, but follow it by an unmap_mapping_range to eliminate the
disconnected pages (freed from pagecache while still mapped in userspace) that
it might have left behind.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Cc: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Miklos Szeredi observes that during truncation of shmem page directories,
info->lock is released to improve latency (after lowering i_size and
next_index to exclude races); but this is quite wrong for holepunching, which
receives no such protection from i_size or next_index, and is left vulnerable
to races with shmem_unuse, shmem_getpage and shmem_writepage.
Hold info->lock throughout when holepunching? No, any user could prevent
rescheduling for far too long. Instead take info->lock just when needed: in
shmem_free_swp when removing the swap entries, and whenever removing a
directory page from the level above. But so long as we remove before
scanning, we can safely skip taking the lock at the lower levels, except at
misaligned start and end of the hole.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Miklos Szeredi observes BUG_ON(!entry) in shmem_writepage() triggered in rare
circumstances, because shmem_truncate_range() erroneously removes partially
truncated directory pages at the end of the range: later reclaim on pages
pointing to these removed directories triggers the BUG. Indeed, and it can
also cause data loss beyond the hole.
Fix this as in the patch proposed by Miklos, but distinguish between "limit"
(how far we need to search: ignore truncation's next_index optimization in the
holepunch case - if there are races it's more consistent to act on the whole
range specified) and "upper_limit" (how far we can free directory pages:
generally we must be careful to keep partially punched pages, but can relax at
end of file - i_size being held stable by i_mutex).
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Cc: Miklos Szeredi <mszeredi@suse.cs>
Cc: Badari Pulavarty <pbadari@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
There is a small problem in handling page bounce.
At the moment blk_max_pfn equals max_pfn, which is in fact not maximum
possible _number_ of a page frame, but the _amount_ of page frames. For
example for the 32bit x86 node with 4Gb RAM, max_pfn = 0x100000, but not
0xFFFF.
request_queue structure has a member q->bounce_pfn and queue needs bounce
pages for the pages _above_ this limit. This routine is handled by
blk_queue_bounce(), where the following check is produced:
if (q->bounce_pfn >= blk_max_pfn)
return;
Assume, that a driver has set q->bounce_pfn to 0xFFFF, but blk_max_pfn
equals 0x10000. In such situation the check above fails and for each bio
we always fall down for iterating over pages tied to the bio.
I want to notice, that for quite a big range of device drivers (ide, md,
...) such problem doesn't happen because they use BLK_BOUNCE_ANY for
bounce_pfn. BLK_BOUNCE_ANY is defined as blk_max_pfn << PAGE_SHIFT, and
then the check above doesn't fail. But for other drivers, which obtain
reuired value from drivers, it fails. For example sata_nv uses
ATA_DMA_MASK or dev->dma_mask.
I propose to use (max_pfn - 1) for blk_max_pfn. And the same for
blk_max_low_pfn. The patch also cleanses some checks related with
bounce_pfn.
Signed-off-by: Vasily Tarasov <vtaras@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
