The patch titled
Subject: readahead: fault retry breaks mmap file read random detection
has been added to the -mm tree. Its filename is
readahead-fault-retry-breaks-mmap-file-read-random-detection.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Shaohua Li <shli@xxxxxxxxxx>
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 <shaohua.li@xxxxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
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(-)
diff -puN arch/arm/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/arm/mm/fault.c
--- a/arch/arm/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/arm/mm/fault.c
@@ -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;
}
}
diff -puN arch/avr32/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/avr32/mm/fault.c
--- a/arch/avr32/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/avr32/mm/fault.c
@@ -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
diff -puN arch/cris/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/cris/mm/fault.c
--- a/arch/cris/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/cris/mm/fault.c
@@ -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
diff -puN arch/hexagon/mm/vm_fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/hexagon/mm/vm_fault.c
--- a/arch/hexagon/mm/vm_fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/hexagon/mm/vm_fault.c
@@ -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;
}
}
diff -puN arch/ia64/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/ia64/mm/fault.c
--- a/arch/ia64/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/ia64/mm/fault.c
@@ -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
diff -puN arch/m68k/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/m68k/mm/fault.c
--- a/arch/m68k/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/m68k/mm/fault.c
@@ -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
diff -puN arch/microblaze/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/microblaze/mm/fault.c
--- a/arch/microblaze/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/microblaze/mm/fault.c
@@ -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
diff -puN arch/mips/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/mips/mm/fault.c
--- a/arch/mips/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/mips/mm/fault.c
@@ -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
diff -puN arch/openrisc/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/openrisc/mm/fault.c
--- a/arch/openrisc/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/openrisc/mm/fault.c
@@ -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
diff -puN arch/powerpc/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/powerpc/mm/fault.c
--- a/arch/powerpc/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/powerpc/mm/fault.c
@@ -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;
}
}
diff -puN arch/s390/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/s390/mm/fault.c
--- a/arch/s390/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/s390/mm/fault.c
@@ -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;
}
diff -puN arch/sh/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/sh/mm/fault.c
--- a/arch/sh/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/sh/mm/fault.c
@@ -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
diff -puN arch/sparc/mm/fault_32.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/sparc/mm/fault_32.c
--- a/arch/sparc/mm/fault_32.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/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 -puN arch/sparc/mm/fault_64.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/sparc/mm/fault_64.c
--- a/arch/sparc/mm/fault_64.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/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
diff -puN arch/tile/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/tile/mm/fault.c
--- a/arch/tile/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/tile/mm/fault.c
@@ -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
diff -puN arch/um/kernel/trap.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/um/kernel/trap.c
--- a/arch/um/kernel/trap.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/um/kernel/trap.c
@@ -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;
}
diff -puN arch/x86/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/x86/mm/fault.c
--- a/arch/x86/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/x86/mm/fault.c
@@ -1202,6 +1202,7 @@ good_area:
/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
* of starvation. */
flags &= ~FAULT_FLAG_ALLOW_RETRY;
+ flags |= FAULT_FLAG_TRIED;
goto retry;
}
}
diff -puN arch/xtensa/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection arch/xtensa/mm/fault.c
--- a/arch/xtensa/mm/fault.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/arch/xtensa/mm/fault.c
@@ -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
diff -puN include/linux/mm.h~readahead-fault-retry-breaks-mmap-file-read-random-detection include/linux/mm.h
--- a/include/linux/mm.h~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/include/linux/mm.h
@@ -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
diff -puN mm/filemap.c~readahead-fault-retry-breaks-mmap-file-read-random-detection mm/filemap.c
--- a/mm/filemap.c~readahead-fault-retry-breaks-mmap-file-read-random-detection
+++ a/mm/filemap.c
@@ -1607,13 +1607,13 @@ 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);
_
Patches currently in -mm which might be from shli@xxxxxxxxxx are
linux-next.patch
readahead-fault-retry-breaks-mmap-file-read-random-detection.patch
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