linux-toradex.git/mm/hugetlb.c, branch v2.6.19-rc2

[PATCH] hugetlb: fix linked list corruption in unmap_hugepage_range()

2006-10-11T18:14:15+00:00

commit fe1668ae5bf0145014c71797febd9ad5670d5d05 causes kernel to oops with
libhugetlbfs test suite.  The problem is that hugetlb pages can be shared
by multiple mappings.  Multiple threads can fight over page->lru in the
unmap path and bad things happen.  We now serialize __unmap_hugepage_range
to void concurrent linked list manipulation.  Such serialization is also
needed for shared page table page on hugetlb area.  This patch will fixed
the bug and also serve as a prepatch for shared page table.

Signed-off-by: Ken Chen 
Cc: Hugh Dickins 
Cc: David Gibson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] enforce proper tlb flush in unmap_hugepage_range

2006-10-04T14:55:12+00:00

Spotted by Hugh that hugetlb page is free'ed back to global pool before
performing any TLB flush in unmap_hugepage_range().  This potentially allow
threads to abuse free-alloc race condition.

The generic tlb gather code is unsuitable to use by hugetlb, I just open
coded a page gathering list and delayed put_page until tlb flush is
performed.

Cc: Hugh Dickins 
Signed-off-by: Ken Chen 
Acked-by: William Irwin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] NUMA: Add zone_to_nid function

2006-09-26T15:48:52+00:00

There are many places where we need to determine the node of a zone.
Currently we use a difficult to read sequence of pointer dereferencing.
Put that into an inline function and use throughout VM.  Maybe we can find
a way to optimize the lookup in the future.

Signed-off-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Hugepages: Use page_to_nid rather than traversing zone pointers

2006-09-26T15:48:52+00:00

I found two location in hugetlb.c where we chase pointer instead of using
page_to_nid().  Page_to_nid is more effective and can get the node directly
from page flags.

Signed-off-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] tightening hugetlb strict accounting

2006-06-23T14:42:48+00:00

Current hugetlb strict accounting for shared mapping always assume mapping
starts at zero file offset and reserves pages between zero and size of the
file.  This assumption often reserves (or lock down) a lot more pages then
necessary if application maps at none zero file offset.  libhugetlbfs is
one example that requires proper reservation on shared mapping starts at
none zero offset.

This patch extends the reservation and hugetlb strict accounting to support
any arbitrary pair of (offset, len), resulting a much more robust and
accurate scheme.  More importantly, it won't lock down any hugetlb pages
outside file mapping.

Signed-off-by: Ken Chen 
Acked-by: Adam Litke 
Cc: David Gibson 
Cc: William Lee Irwin III 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] hugetlb: don't allow free hugetlb count fall below reserved count

2006-03-31T20:18:50+00:00

With strict page reservation, I think kernel should enforce number of free
hugetlb page don't fall below reserved count.  Currently it is possible in
the sysctl path.  Add proper check in sysctl to disallow that.

Signed-off-by: Ken Chen 
Cc: David Gibson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] fix extra page ref count in follow_hugetlb_page

2006-03-31T20:18:49+00:00

git-commit: d5d4b0aa4e1430d73050babba999365593bdb9d2
"[PATCH] optimize follow_hugetlb_page" breaks mlock on hugepage areas.

I mis-interpret pages argument and made get_page() unconditional.  It
should only get a ref count when "pages" argument is non-null.

Credit goes to Adam Litke who spotted the bug.

Signed-off-by: Ken Chen 
Acked-by: Adam Litke 
Cc: David Gibson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] mm: hugetlb alloc_fresh_huge_page bogus node loop fix

2006-03-22T15:54:06+00:00

Fix bogus node loop in hugetlb.c alloc_fresh_huge_page(), which was
assuming that nodes are numbered contiguously from 0 to num_online_nodes().
Once the hotplug folks get this far, that will be false.

Signed-off-by: Paul Jackson 
Acked-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] optimize follow_hugetlb_page

2006-03-22T15:54:04+00:00

follow_hugetlb_page() walks a range of user virtual address and then fills
in list of struct page * into an array that is passed from the argument
list.  It also gets a reference count via get_page().  For compound page,
get_page() actually traverse back to head page via page_private() macro and
then adds a reference count to the head page.  Since we are doing a virt to
pte look up, kernel already has a struct page pointer into the head page.
So instead of traverse into the small unit page struct and then follow a
link back to the head page, optimize that with incrementing the reference
count directly on the head page.

The benefit is that we don't take a cache miss on accessing page struct for
the corresponding user address and more importantly, not to pollute the
cache with a "not very useful" round trip of pointer chasing.  This adds a
moderate performance gain on an I/O intensive database transaction
workload.

Signed-off-by: Ken Chen 
Cc: David Gibson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] hugepage: Make {alloc,free}_huge_page() local

2006-03-22T15:54:03+00:00

Originally, mm/hugetlb.c just handled the hugepage physical allocation path
and its {alloc,free}_huge_page() functions were used from the arch specific
hugepage code.  These days those functions are only used with mm/hugetlb.c
itself.  Therefore, this patch makes them static and removes their
prototypes from hugetlb.h.  This requires a small rearrangement of code in
mm/hugetlb.c to avoid a forward declaration.

This patch causes no regressions on the libhugetlbfs testsuite (ppc64,
POWER5).

Signed-off-by: David Gibson 
Cc: William Lee Irwin III 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds