Revision 3ad33b2436b545cbe8b28e53f3710432cad457ab authored by Lee Schermerhorn on 15 November 2007, 00:59:10 UTC, committed by Linus Torvalds on 15 November 2007, 02:45:38 UTC
We hit the BUG_ON() in mm/rmap.c:vma_address() when trying to migrate via mbind(MPOL_MF_MOVE) a non-anon region that spans multiple vmas. For anon-regions, we just fail to migrate any pages beyond the 1st vma in the range. This occurs because do_mbind() collects a list of pages to migrate by calling check_range(). check_range() walks the task's mm, spanning vmas as necessary, to collect the migratable pages into a list. Then, do_mbind() calls migrate_pages() passing the list of pages, a function to allocate new pages based on vma policy [new_vma_page()], and a pointer to the first vma of the range. For each page in the list, new_vma_page() calls page_address_in_vma() passing the page and the vma [first in range] to obtain the address to get for alloc_page_vma(). The page address is needed to get interleaving policy correct. If the pages in the list come from multiple vmas, eventually, new_page_address() will pass that page to page_address_in_vma() with the incorrect vma. For !PageAnon pages, this will result in a bug check in rmap.c:vma_address(). For anon pages, vma_address() will just return EFAULT and fail the migration. This patch modifies new_vma_page() to check the return value from page_address_in_vma(). If the return value is EFAULT, new_vma_page() searchs forward via vm_next for the vma that maps the page--i.e., that does not return EFAULT. This assumes that the pages in the list handed to migrate_pages() is in address order. This is currently case. The patch documents this assumption in a new comment block for new_vma_page(). If new_vma_page() cannot locate the vma mapping the page in a forward search in the mm, it will pass a NULL vma to alloc_page_vma(). This will result in the allocation using the task policy, if any, else system default policy. This situation is unlikely, but the patch documents this behavior with a comment. Note, this patch results in restarting from the first vma in a multi-vma range each time new_vma_page() is called. If this is not acceptable, we can make the vma argument a pointer, both in new_vma_page() and it's caller unmap_and_move() so that the value held by the loop in migrate_pages() always passes down the last vma in which a page was found. This will require changes to all new_page_t functions passed to migrate_pages(). Is this necessary? For this patch to work, we can't bug check in vma_address() for pages outside the argument vma. This patch removes the BUG_ON(). All other callers [besides new_vma_page()] already check the return status. Tested on x86_64, 4 node NUMA platform. Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com> Acked-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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upd64083.h
/*
* upd6408x - NEC Electronics 3-Dimensional Y/C separation input defines
*
* 2006 by Hans Verkuil (hverkuil@xs4all.nl)
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#ifndef _UPD64083_H_
#define _UPD64083_H_
/* There are two bits of information that the driver needs in order
to select the correct routing: the operating mode and the selection
of the Y input (external or internal).
The first two operating modes expect a composite signal on the Y input,
the second two operating modes use both the Y and C inputs.
Normally YCS_MODE is used for tuner and composite inputs, and the
YCNR mode is used for S-Video inputs.
The external Y-ADC is selected when the composite input comes from a
upd64031a ghost reduction device. If this device is not present, or
the input is a S-Video signal, then the internal Y-ADC input should
be used. */
/* Operating modes: */
/* YCS mode: Y/C separation (burst locked clocking) */
#define UPD64083_YCS_MODE 0
/* YCS+ mode: 2D Y/C separation and YCNR (burst locked clocking) */
#define UPD64083_YCS_PLUS_MODE 1
/* Note: the following two modes cannot be used in combination with the
external Y-ADC. */
/* MNNR mode: frame comb type YNR+C delay (line locked clocking) */
#define UPD64083_MNNR_MODE 2
/* YCNR mode: frame recursive YCNR (burst locked clocking) */
#define UPD64083_YCNR_MODE 3
/* Select external Y-ADC: this should be set if this device is used in
combination with the upd64031a ghost reduction device.
Otherwise leave at 0 (use internal Y-ADC). */
#define UPD64083_EXT_Y_ADC (1 << 2)
#endif
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