From 45cac65b0fcd287ebb877b141d40ba9bbe8e5da7 Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Mon, 8 Oct 2012 16:32:19 -0700 Subject: readahead: fault retry breaks mmap file read random detection .fault now can retry. The retry can break state machine of .fault. In filemap_fault, if page is miss, ra->mmap_miss is increased. In the second try, since the page is in page cache now, ra->mmap_miss is decreased. And these are done in one fault, so we can't detect random mmap file access. Add a new flag to indicate .fault is tried once. In the second try, skip ra->mmap_miss decreasing. The filemap_fault state machine is ok with it. I only tested x86, didn't test other archs, but looks the change for other archs is obvious, but who knows :) Signed-off-by: Shaohua Li Cc: Rik van Riel Cc: Wu Fengguang Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- arch/sparc/mm/fault_32.c | 1 + arch/sparc/mm/fault_64.c | 1 + 2 files changed, 2 insertions(+) (limited to 'arch/sparc/mm') diff --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c index 77ac917be152..e98bfda205a2 100644 --- a/arch/sparc/mm/fault_32.c +++ b/arch/sparc/mm/fault_32.c @@ -265,6 +265,7 @@ good_area: } if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* No need to up_read(&mm->mmap_sem) as we would * have already released it in __lock_page_or_retry diff --git a/arch/sparc/mm/fault_64.c b/arch/sparc/mm/fault_64.c index 1fe0429b6314..413d29263304 100644 --- a/arch/sparc/mm/fault_64.c +++ b/arch/sparc/mm/fault_64.c @@ -452,6 +452,7 @@ good_area: } if (fault & VM_FAULT_RETRY) { flags &= ~FAULT_FLAG_ALLOW_RETRY; + flags |= FAULT_FLAG_TRIED; /* No need to up_read(&mm->mmap_sem) as we would * have already released it in __lock_page_or_retry -- cgit v1.2.3