From e0f23603fb2607315ce52432cc4225df410828cf Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Fri, 23 Jun 2006 02:05:48 -0700 Subject: [PATCH] Remove semi-softlockup from invalidate_mapping_pages If invalidate_mapping_pages is called to invalidate a very large mapping (e.g. a very large block device) and if the only active page in that device is near the end (or at least, at a very large index), such as, say, the superblock of an md array, and if that page happens to be locked when invalidate_mapping_pages is called, then pagevec_lookup will return this page and as it is locked, 'next' will be incremented and pagevec_lookup will be called again. and again. and again. while we count from 0 upto a very large number. We should really always set 'next' to 'page->index+1' before going around the loop again, not just if the page isn't locked. Cc: "Steinar H. Gunderson" Signed-off-by: Neil Brown Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/truncate.c | 22 ++++++++++++++++------ 1 file changed, 16 insertions(+), 6 deletions(-) diff --git a/mm/truncate.c b/mm/truncate.c index 6cb3fff25f67..cf1b015df4a7 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -230,14 +230,24 @@ unsigned long invalidate_mapping_pages(struct address_space *mapping, pagevec_lookup(&pvec, mapping, next, PAGEVEC_SIZE)) { for (i = 0; i < pagevec_count(&pvec); i++) { struct page *page = pvec.pages[i]; + pgoff_t index; + int lock_failed; - if (TestSetPageLocked(page)) { - next++; - continue; - } - if (page->index > next) - next = page->index; + lock_failed = TestSetPageLocked(page); + + /* + * We really shouldn't be looking at the ->index of an + * unlocked page. But we're not allowed to lock these + * pages. So we rely upon nobody altering the ->index + * of this (pinned-by-us) page. + */ + index = page->index; + if (index > next) + next = index; next++; + if (lock_failed) + continue; + if (PageDirty(page) || PageWriteback(page)) goto unlock; if (page_mapped(page)) -- cgit v1.2.2