From: Shaohua Li <shli@kernel.org>
To: linux-mm@kvack.org
Cc: fengguang.wu@intel.com, akpm@linux-foundation.org, riel@redhat.com
Subject: [patch]readahead: fault retry breaks mmap file read random detection
Date: Wed, 22 Aug 2012 11:40:12 +0800 [thread overview]
Message-ID: <20120822034012.GA24099@kernel.org> (raw)
.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 <shaohua.li@fusionio.com>
---
arch/arm/mm/fault.c | 1 +
arch/avr32/mm/fault.c | 1 +
arch/cris/mm/fault.c | 1 +
arch/hexagon/mm/vm_fault.c | 1 +
arch/ia64/mm/fault.c | 1 +
arch/m68k/mm/fault.c | 1 +
arch/microblaze/mm/fault.c | 1 +
arch/mips/mm/fault.c | 1 +
arch/openrisc/mm/fault.c | 1 +
arch/powerpc/mm/fault.c | 1 +
arch/s390/mm/fault.c | 1 +
arch/sh/mm/fault.c | 1 +
arch/sparc/mm/fault_32.c | 1 +
arch/sparc/mm/fault_64.c | 1 +
arch/tile/mm/fault.c | 1 +
arch/um/kernel/trap.c | 1 +
arch/x86/mm/fault.c | 1 +
arch/xtensa/mm/fault.c | 1 +
include/linux/mm.h | 1 +
mm/filemap.c | 4 ++--
20 files changed, 21 insertions(+), 2 deletions(-)
Index: linux/arch/x86/mm/fault.c
===================================================================
--- linux.orig/arch/x86/mm/fault.c 2012-08-22 09:51:22.939527887 +0800
+++ linux/arch/x86/mm/fault.c 2012-08-22 09:52:22.818774975 +0800
@@ -1201,6 +1201,7 @@ good_area:
/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
* of starvation. */
flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ flags |= FAULT_FLAG_TRIED;
goto retry;
}
}
Index: linux/include/linux/mm.h
===================================================================
--- linux.orig/include/linux/mm.h 2012-08-22 09:51:23.087526029 +0800
+++ linux/include/linux/mm.h 2012-08-22 09:52:22.822775020 +0800
@@ -157,6 +157,7 @@ extern pgprot_t protection_map[16];
#define FAULT_FLAG_ALLOW_RETRY 0x08 /* Retry fault if blocking */
#define FAULT_FLAG_RETRY_NOWAIT 0x10 /* Don't drop mmap_sem and wait when retrying */
#define FAULT_FLAG_KILLABLE 0x20 /* The fault task is in SIGKILL killable region */
+#define FAULT_FLAG_TRIED 0x40 /* second try */
/*
* This interface is used by x86 PAT code to identify a pfn mapping that is
Index: linux/mm/filemap.c
===================================================================
--- linux.orig/mm/filemap.c 2012-08-22 09:51:23.079526129 +0800
+++ linux/mm/filemap.c 2012-08-22 09:52:22.822775020 +0800
@@ -1611,13 +1611,13 @@ int filemap_fault(struct vm_area_struct
* Do we have something in the page cache already?
*/
page = find_get_page(mapping, offset);
- if (likely(page)) {
+ if (likely(page) && !(vmf->flags & FAULT_FLAG_TRIED)) {
/*
* We found the page, so try async readahead before
* waiting for the lock.
*/
do_async_mmap_readahead(vma, ra, file, page, offset);
- } else {
+ } else if (!page) {
/* No page in the page cache at all */
do_sync_mmap_readahead(vma, ra, file, offset);
count_vm_event(PGMAJFAULT);
Index: linux/arch/arm/mm/fault.c
===================================================================
--- linux.orig/arch/arm/mm/fault.c 2012-08-22 09:51:22.899528391 +0800
+++ linux/arch/arm/mm/fault.c 2012-08-22 09:52:22.822775020 +0800
@@ -336,6 +336,7 @@ retry:
/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
* of starvation. */
flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ flags |= FAULT_FLAG_TRIED;
goto retry;
}
}
Index: linux/arch/avr32/mm/fault.c
===================================================================
--- linux.orig/arch/avr32/mm/fault.c 2012-08-22 09:51:23.035526683 +0800
+++ linux/arch/avr32/mm/fault.c 2012-08-22 09:52:22.822775020 +0800
@@ -152,6 +152,7 @@ good_area:
tsk->min_flt++;
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
Index: linux/arch/cris/mm/fault.c
===================================================================
--- linux.orig/arch/cris/mm/fault.c 2012-08-22 09:51:23.059526379 +0800
+++ linux/arch/cris/mm/fault.c 2012-08-22 09:52:22.822775020 +0800
@@ -186,6 +186,7 @@ retry:
tsk->min_flt++;
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
Index: linux/arch/hexagon/mm/vm_fault.c
===================================================================
--- linux.orig/arch/hexagon/mm/vm_fault.c 2012-08-22 09:51:22.915528191 +0800
+++ linux/arch/hexagon/mm/vm_fault.c 2012-08-22 09:52:22.822775020 +0800
@@ -113,6 +113,7 @@ good_area:
current->min_flt++;
if (fault & VM_FAULT_RETRY) {
flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ flags |= FAULT_FLAG_TRIED;
goto retry;
}
}
Index: linux/arch/ia64/mm/fault.c
===================================================================
--- linux.orig/arch/ia64/mm/fault.c 2012-08-22 09:51:22.967527537 +0800
+++ linux/arch/ia64/mm/fault.c 2012-08-22 09:52:22.822775020 +0800
@@ -184,6 +184,7 @@ retry:
current->min_flt++;
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
Index: linux/arch/m68k/mm/fault.c
===================================================================
--- linux.orig/arch/m68k/mm/fault.c 2012-08-22 09:51:23.015526933 +0800
+++ linux/arch/m68k/mm/fault.c 2012-08-22 09:52:22.822775020 +0800
@@ -170,6 +170,7 @@ good_area:
/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
* of starvation. */
flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ flags |= FAULT_FLAG_TRIED;
/*
* No need to up_read(&mm->mmap_sem) as we would
Index: linux/arch/microblaze/mm/fault.c
===================================================================
--- linux.orig/arch/microblaze/mm/fault.c 2012-08-22 09:51:22.995527183 +0800
+++ linux/arch/microblaze/mm/fault.c 2012-08-22 09:52:22.822775020 +0800
@@ -233,6 +233,7 @@ good_area:
current->min_flt++;
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
Index: linux/arch/mips/mm/fault.c
===================================================================
--- linux.orig/arch/mips/mm/fault.c 2012-08-22 09:51:22.975527437 +0800
+++ linux/arch/mips/mm/fault.c 2012-08-22 09:52:22.822775020 +0800
@@ -171,6 +171,7 @@ 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
Index: linux/arch/openrisc/mm/fault.c
===================================================================
--- linux.orig/arch/openrisc/mm/fault.c 2012-08-22 09:51:23.027526783 +0800
+++ linux/arch/openrisc/mm/fault.c 2012-08-22 09:52:22.822775020 +0800
@@ -183,6 +183,7 @@ good_area:
tsk->min_flt++;
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
Index: linux/arch/powerpc/mm/fault.c
===================================================================
--- linux.orig/arch/powerpc/mm/fault.c 2012-08-22 09:51:22.987527285 +0800
+++ linux/arch/powerpc/mm/fault.c 2012-08-22 09:52:22.822775020 +0800
@@ -450,6 +450,7 @@ good_area:
/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
* of starvation. */
flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ flags |= FAULT_FLAG_TRIED;
goto retry;
}
}
Index: linux/arch/s390/mm/fault.c
===================================================================
--- linux.orig/arch/s390/mm/fault.c 2012-08-22 09:51:23.067526279 +0800
+++ linux/arch/s390/mm/fault.c 2012-08-22 09:52:22.822775020 +0800
@@ -367,6 +367,7 @@ retry:
/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
* of starvation. */
flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ flags |= FAULT_FLAG_TRIED;
down_read(&mm->mmap_sem);
goto retry;
}
Index: linux/arch/sh/mm/fault.c
===================================================================
--- linux.orig/arch/sh/mm/fault.c 2012-08-22 09:51:22.907528291 +0800
+++ linux/arch/sh/mm/fault.c 2012-08-22 09:52:22.822775020 +0800
@@ -504,6 +504,7 @@ 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
Index: linux/arch/sparc/mm/fault_32.c
===================================================================
--- linux.orig/arch/sparc/mm/fault_32.c 2012-08-22 09:51:22.955527687 +0800
+++ linux/arch/sparc/mm/fault_32.c 2012-08-22 09:52:22.826775037 +0800
@@ -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
Index: linux/arch/sparc/mm/fault_64.c
===================================================================
--- linux.orig/arch/sparc/mm/fault_64.c 2012-08-22 09:51:22.947527787 +0800
+++ linux/arch/sparc/mm/fault_64.c 2012-08-22 09:52:22.826775037 +0800
@@ -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
Index: linux/arch/tile/mm/fault.c
===================================================================
--- linux.orig/arch/tile/mm/fault.c 2012-08-22 09:51:23.007527033 +0800
+++ linux/arch/tile/mm/fault.c 2012-08-22 09:52:22.826775037 +0800
@@ -454,6 +454,7 @@ good_area:
tsk->min_flt++;
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
Index: linux/arch/um/kernel/trap.c
===================================================================
--- linux.orig/arch/um/kernel/trap.c 2012-08-22 09:51:23.047526530 +0800
+++ linux/arch/um/kernel/trap.c 2012-08-22 09:52:22.826775037 +0800
@@ -89,6 +89,7 @@ good_area:
current->min_flt++;
if (fault & VM_FAULT_RETRY) {
flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ flags |= FAULT_FLAG_TRIED;
goto retry;
}
Index: linux/arch/xtensa/mm/fault.c
===================================================================
--- linux.orig/arch/xtensa/mm/fault.c 2012-08-22 09:51:22.927528040 +0800
+++ linux/arch/xtensa/mm/fault.c 2012-08-22 09:52:22.826775037 +0800
@@ -126,6 +126,7 @@ good_area:
current->min_flt++;
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
--
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next reply other threads:[~2012-08-22 3:40 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-22 3:40 Shaohua Li [this message]
2012-08-22 15:40 ` [patch]readahead: fault retry breaks mmap file read random detection Rik van Riel
2012-08-23 1:10 ` Shaohua Li
2012-08-30 17:21 ` Minchan Kim
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