Messages in this thread Patch in this message | | | From | Zach Brown <> | Subject | [PATCH] AOP_TRUNCATED_PAGE victims in read_pages() belong in the LRU | Date | Wed, 3 May 2006 13:07:55 -0700 (PDT) |
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AOP_TRUNCATED_PAGE victims in read_pages() belong in the LRU
Nick Piggin rightly pointed out that the introduction of AOP_TRUNCATED_PAGE to read_pages() was wrong to leave A_T_P victim pages in the page cache but not put them in the LRU. Failing to do so hid them from the VM.
A_T_P just means that the aop method unlocked the page rather than performing IO. It would be very rare that the page was truncated between the unlock and testing A_T_P. So we leave the pages in the LRU for likely reuse soon rather than backing them back out of the page cache. We do this by matching the behaviour before the A_T_P introduction which added pages to the LRU regardless of what ->readpage() did.
This doesn't include the unrelated cleanup in Nick's initial fix which changed read_pages() to return void to match its only caller's behaviour of ignoring errors.
Signed-off-by: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Zach Brown <zach.brown@oracle.com> ---
mm/readahead.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-)
Index: 2.6.17-rc3-git7-read_pages-fix/mm/readahead.c =================================================================== --- 2.6.17-rc3-git7-read_pages-fix.orig/mm/readahead.c +++ 2.6.17-rc3-git7-read_pages-fix/mm/readahead.c @@ -182,14 +182,11 @@ static int read_pages(struct address_spa list_del(&page->lru); if (!add_to_page_cache(page, mapping, page->index, GFP_KERNEL)) { - ret = mapping->a_ops->readpage(filp, page); - if (ret != AOP_TRUNCATED_PAGE) { - if (!pagevec_add(&lru_pvec, page)) - __pagevec_lru_add(&lru_pvec); - continue; - } /* else fall through to release */ - } - page_cache_release(page); + mapping->a_ops->readpage(filp, page); + if (!pagevec_add(&lru_pvec, page)) + __pagevec_lru_add(&lru_pvec); + } else + page_cache_release(page); } pagevec_lru_add(&lru_pvec); ret = 0; - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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