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@fusionio.com> Cc: Rik van Riel <riel@redhat.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

commit: 45cac65b0fcd287ebb877b141d40ba9bbe8e5da7 [log] [tgz]
author: Shaohua Li <shli@kernel.org> Mon Oct 08 16:32:19 2012 -0700
committer: Linus Torvalds <torvalds@linux-foundation.org> Tue Oct 09 16:22:47 2012 +0900
tree: 30ed25c91aaeed153de51a78d171cb14582e383f
parent: e79bee24fd6134f90af4228cfebd010136d67631 [diff]
diff --git a/arch/arm/mm/fault.c b/arch/arm/mm/fault.c
index c3bd834..5dbf13f 100644
--- a/arch/arm/mm/fault.c
+++ b/arch/arm/mm/fault.c

@@ -336,6 +336,7 @@
 			/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
 			* of starvation. */
 			flags &= ~FAULT_FLAG_ALLOW_RETRY;
+			flags |= FAULT_FLAG_TRIED;
 			goto retry;
 		}
 	}

diff --git a/arch/avr32/mm/fault.c b/arch/avr32/mm/fault.c
index b92e609..b2f2d2d 100644
--- a/arch/avr32/mm/fault.c
+++ b/arch/avr32/mm/fault.c

@@ -152,6 +152,7 @@
 			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 --git a/arch/cris/mm/fault.c b/arch/cris/mm/fault.c
index 45fd542..73312ab 100644
--- a/arch/cris/mm/fault.c
+++ b/arch/cris/mm/fault.c

@@ -186,6 +186,7 @@
 			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 --git a/arch/hexagon/mm/vm_fault.c b/arch/hexagon/mm/vm_fault.c
index 06695cc..513b74c 100644
--- a/arch/hexagon/mm/vm_fault.c
+++ b/arch/hexagon/mm/vm_fault.c

@@ -113,6 +113,7 @@
 				current->min_flt++;
 			if (fault & VM_FAULT_RETRY) {
 				flags &= ~FAULT_FLAG_ALLOW_RETRY;
+				flags |= FAULT_FLAG_TRIED;
 				goto retry;
 			}
 		}

diff --git a/arch/ia64/mm/fault.c b/arch/ia64/mm/fault.c
index 8443daf..6cf0341 100644
--- a/arch/ia64/mm/fault.c
+++ b/arch/ia64/mm/fault.c

@@ -184,6 +184,7 @@
 			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 --git a/arch/m68k/mm/fault.c b/arch/m68k/mm/fault.c
index aeebbb7..a563727 100644
--- a/arch/m68k/mm/fault.c
+++ b/arch/m68k/mm/fault.c

@@ -170,6 +170,7 @@
 			/* 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 --git a/arch/microblaze/mm/fault.c b/arch/microblaze/mm/fault.c
index eb365d6..714b35a 100644
--- a/arch/microblaze/mm/fault.c
+++ b/arch/microblaze/mm/fault.c

@@ -233,6 +233,7 @@
 			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 --git a/arch/mips/mm/fault.c b/arch/mips/mm/fault.c
index c14f6df..9f51348 100644
--- a/arch/mips/mm/fault.c
+++ b/arch/mips/mm/fault.c

@@ -171,6 +171,7 @@
 		}
 		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 --git a/arch/openrisc/mm/fault.c b/arch/openrisc/mm/fault.c
index 40f850e..e2bfafc 100644
--- a/arch/openrisc/mm/fault.c
+++ b/arch/openrisc/mm/fault.c

@@ -183,6 +183,7 @@
 			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 --git a/arch/powerpc/mm/fault.c b/arch/powerpc/mm/fault.c
index 5495ebe9..0a6b283 100644
--- a/arch/powerpc/mm/fault.c
+++ b/arch/powerpc/mm/fault.c

@@ -451,6 +451,7 @@
 			/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
 			 * of starvation. */
 			flags &= ~FAULT_FLAG_ALLOW_RETRY;
+			flags |= FAULT_FLAG_TRIED;
 			goto retry;
 		}
 	}

diff --git a/arch/s390/mm/fault.c b/arch/s390/mm/fault.c
index ac9122c..04ad400 100644
--- a/arch/s390/mm/fault.c
+++ b/arch/s390/mm/fault.c

@@ -367,6 +367,7 @@
 			/* 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 --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 3bdc1ad..cbbdcad 100644
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c

@@ -504,6 +504,7 @@
 		}
 		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 --git a/arch/sparc/mm/fault_32.c b/arch/sparc/mm/fault_32.c
index 77ac917..e98bfda 100644
--- a/arch/sparc/mm/fault_32.c
+++ b/arch/sparc/mm/fault_32.c

@@ -265,6 +265,7 @@
 		}
 		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 1fe0429..413d292 100644
--- a/arch/sparc/mm/fault_64.c
+++ b/arch/sparc/mm/fault_64.c

@@ -452,6 +452,7 @@
 		}
 		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/tile/mm/fault.c b/arch/tile/mm/fault.c
index 84ce7ab..fe811fa 100644
--- a/arch/tile/mm/fault.c
+++ b/arch/tile/mm/fault.c

@@ -454,6 +454,7 @@
 			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 --git a/arch/um/kernel/trap.c b/arch/um/kernel/trap.c
index 0353b98..0f00e9c 100644
--- a/arch/um/kernel/trap.c
+++ b/arch/um/kernel/trap.c

@@ -89,6 +89,7 @@
 				current->min_flt++;
 			if (fault & VM_FAULT_RETRY) {
 				flags &= ~FAULT_FLAG_ALLOW_RETRY;
+				flags |= FAULT_FLAG_TRIED;
 
 				goto retry;
 			}

diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
index a530b23..8e13ecb 100644
--- a/arch/x86/mm/fault.c
+++ b/arch/x86/mm/fault.c

@@ -1220,6 +1220,7 @@
 			/* Clear FAULT_FLAG_ALLOW_RETRY to avoid any risk
 			 * of starvation. */
 			flags &= ~FAULT_FLAG_ALLOW_RETRY;
+			flags |= FAULT_FLAG_TRIED;
 			goto retry;
 		}
 	}

diff --git a/arch/xtensa/mm/fault.c b/arch/xtensa/mm/fault.c
index 5a74c53..2c2f710 100644
--- a/arch/xtensa/mm/fault.c
+++ b/arch/xtensa/mm/fault.c

@@ -126,6 +126,7 @@
 			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
commit	45cac65b0fcd287ebb877b141d40ba9bbe8e5da7	[log] [tgz]
author	Shaohua Li <shli@kernel.org>	Mon Oct 08 16:32:19 2012 -0700
committer	Linus Torvalds <torvalds@linux-foundation.org>	Tue Oct 09 16:22:47 2012 +0900
tree	30ed25c91aaeed153de51a78d171cb14582e383f
parent	e79bee24fd6134f90af4228cfebd010136d67631 [diff]