Messages in this thread Patch in this message | | | Date | Thu, 17 Apr 2008 15:38:18 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: Warning on memory offline (possible in migration ?) |
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On Thu, 17 Apr 2008 09:19:30 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote: > > I'd expect that you could reproduce this by disabling readahead with > > fadvise(POSIX_FADV_RANDOM) and then issuing the above four reads. > > > Thank you for advice. I'll try. > (Added lkml to CC:)
What happens: When I do memory offline on ia64/NUMA box, __set_page_dirty_buffers() printed out WARNINGS because the page under migration is not up-to-date.
Following is my investigation.
Assume 16k pages / 4 buffers of 4096bytes block (ext3). 4 buffers on a page of ext3.
At page offlining, we can find a page which is not up-to-date. But all buffers of the page seems up-to-date.
buffers on a page by prink(). buffer 0, block_nr= some vaule, state= BH_uptodate | BH_Req| BH_Mapped buffer 1, block_nr= -1, state= BH_uptodate buffer 2, block_nr= -1, state= BH_uptodate buffer 3, block_nr= -1, state= BH_uptodate
It seems no I/O for 3 buffers. It's because the page is the last page of inode and blocks for buffer[1,2,3] is not assgined. (maybe BH_uptodate is set by block_write_full_page().
Adding below check can hide the warning....but I can't say this is correct. Can we set this page dirty silently in this case ?
=== + +static int check_fragment_page(struct page *page, struct address_space *mapping ) +{ + struct inode *inode = mapping->host; + unsigned long lastblock, coverblock; + + if (!page_has_buffers(page)) + return 0; + + lastblock = (i_size_read(inode) - 1) >> inode->i_blkbits; + coverblock = (page->index + 1) << (PAGE_SHIFT - inode->i_blkbits); + + return coverblock > lastblock; +} + + + static int __set_page_dirty(struct page *page, struct address_space *mapping, int warn) { @@ -717,7 +734,9 @@ static int __set_page_dirty(struct page
write_lock_irq(&mapping->tree_lock); if (page->mapping) { /* Race with truncate? */ - WARN_ON_ONCE(warn && !PageUptodate(page)); + WARN_ON_ONCE(warn + && !PageUptodate(page) + && !check_fragment_page(page, mapping));
if (mapping_cap_account_dirty(mapping)) { __inc_zone_page_state(page, NR_FILE_DIRTY); == Thanks, -Kame
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