The patch titled
Subject: mm: prepare for removal of obsolete /proc/sys/vm/nr_pdflush_threads
has been added to the -mm tree. Its filename is
mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads.patch
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From: Wanpeng Li <liwp@xxxxxxxxxxxxxxxxxx>
Subject: mm: prepare for removal of obsolete /proc/sys/vm/nr_pdflush_threads
Since per-BDI flusher threads were introduced in 2.6, the pdflush
mechanism is not used any more. But the old interface exported through
/proc/sys/vm/nr_pdflush_threads still exists and is obviously useless.
For back-compatibility, printk warning information and return 2 to notify
the users that the interface is removed.
Signed-off-by: Wanpeng Li <liwp@xxxxxxxxxxxxxxxxxx>
Cc: Wu Fengguang <fengguang.wu@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/ABI/obsolete/proc-sys-vm-nr_pdflush_threads | 5 ++
Documentation/feature-removal-schedule.txt | 8 ++++
Documentation/sysctl/vm.txt | 11 -----
fs/fs-writeback.c | 5 --
include/linux/backing-dev.h | 3 +
include/linux/writeback.h | 5 --
kernel/sysctl.c | 8 +---
kernel/sysctl_binary.c | 2 -
mm/backing-dev.c | 20 ++++++++++
9 files changed, 40 insertions(+), 27 deletions(-)
diff -puN /dev/null Documentation/ABI/obsolete/proc-sys-vm-nr_pdflush_threads
--- /dev/null
+++ a/Documentation/ABI/obsolete/proc-sys-vm-nr_pdflush_threads
@@ -0,0 +1,5 @@
+What: /proc/sys/vm/nr_pdflush_threads
+Date: June 2012
+Contact: Wanpeng Li <liwp@xxxxxxxxxxxxxxxxxx>
+Description: Since pdflush is replaced by per-BDI flusher, the interface of old pdflush
+ exported in /proc/sys/vm/ should be removed.
diff -puN Documentation/feature-removal-schedule.txt~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads Documentation/feature-removal-schedule.txt
--- a/Documentation/feature-removal-schedule.txt~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads
+++ a/Documentation/feature-removal-schedule.txt
@@ -13,6 +13,14 @@ Who: Jim Cromie <jim.cromie@xxxxxxxxx>,
---------------------------
+What: /proc/sys/vm/nr_pdflush_threads
+When: 2012
+Why: Since pdflush is deprecated, the interface exported in /proc/sys/vm/
+ should be removed.
+Who: Wanpeng Li <liwp@xxxxxxxxxxxxxxxxxx>
+
+---------------------------
+
What: CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
When: 2012
Why: This optional sub-feature of APM is of dubious reliability,
diff -puN Documentation/sysctl/vm.txt~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads Documentation/sysctl/vm.txt
--- a/Documentation/sysctl/vm.txt~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads
+++ a/Documentation/sysctl/vm.txt
@@ -42,7 +42,6 @@ Currently, these files are in /proc/sys/
- mmap_min_addr
- nr_hugepages
- nr_overcommit_hugepages
-- nr_pdflush_threads
- nr_trim_pages (only if CONFIG_MMU=n)
- numa_zonelist_order
- oom_dump_tasks
@@ -426,16 +425,6 @@ See Documentation/vm/hugetlbpage.txt
==============================================================
-nr_pdflush_threads
-
-The current number of pdflush threads. This value is read-only.
-The value changes according to the number of dirty pages in the system.
-
-When necessary, additional pdflush threads are created, one per second, up to
-nr_pdflush_threads_max.
-
-==============================================================
-
nr_trim_pages
This is available only on NOMMU kernels.
diff -puN fs/fs-writeback.c~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads fs/fs-writeback.c
--- a/fs/fs-writeback.c~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads
+++ a/fs/fs-writeback.c
@@ -52,11 +52,6 @@ struct wb_writeback_work {
struct completion *done; /* set if the caller waits */
};
-/*
- * We don't actually have pdflush, but this one is exported though /proc...
- */
-int nr_pdflush_threads;
-
/**
* writeback_in_progress - determine whether there is writeback in progress
* @bdi: the device's backing_dev_info structure.
diff -puN include/linux/backing-dev.h~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads include/linux/backing-dev.h
--- a/include/linux/backing-dev.h~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads
+++ a/include/linux/backing-dev.h
@@ -17,6 +17,7 @@
#include <linux/timer.h>
#include <linux/writeback.h>
#include <linux/atomic.h>
+#include <linux/sysctl.h>
struct page;
struct device;
@@ -304,6 +305,8 @@ void clear_bdi_congested(struct backing_
void set_bdi_congested(struct backing_dev_info *bdi, int sync);
long congestion_wait(int sync, long timeout);
long wait_iff_congested(struct zone *zone, int sync, long timeout);
+int pdflush_proc_obsolete(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos);
static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
{
diff -puN include/linux/writeback.h~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads include/linux/writeback.h
--- a/include/linux/writeback.h~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads
+++ a/include/linux/writeback.h
@@ -189,9 +189,4 @@ void tag_pages_for_writeback(struct addr
void account_page_redirty(struct page *page);
-/* pdflush.c */
-extern int nr_pdflush_threads; /* Global so it can be exported to sysctl
- read-only. */
-
-
#endif /* WRITEBACK_H */
diff -puN kernel/sysctl.c~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads kernel/sysctl.c
--- a/kernel/sysctl.c~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads
+++ a/kernel/sysctl.c
@@ -1106,11 +1106,9 @@ static struct ctl_table vm_table[] = {
.extra1 = &zero,
},
{
- .procname = "nr_pdflush_threads",
- .data = &nr_pdflush_threads,
- .maxlen = sizeof nr_pdflush_threads,
- .mode = 0444 /* read-only*/,
- .proc_handler = proc_dointvec,
+ .procname = "nr_pdflush_threads",
+ .mode = 0444 /* read-only */,
+ .proc_handler = pdflush_proc_obsolete,
},
{
.procname = "swappiness",
diff -puN kernel/sysctl_binary.c~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads kernel/sysctl_binary.c
--- a/kernel/sysctl_binary.c~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads
+++ a/kernel/sysctl_binary.c
@@ -147,7 +147,7 @@ static const struct bin_table bin_vm_tab
{ CTL_INT, VM_DIRTY_RATIO, "dirty_ratio" },
/* VM_DIRTY_WB_CS "dirty_writeback_centisecs" no longer used */
/* VM_DIRTY_EXPIRE_CS "dirty_expire_centisecs" no longer used */
- { CTL_INT, VM_NR_PDFLUSH_THREADS, "nr_pdflush_threads" },
+ /* VM_NR_PDFLUSH_THREADS "nr_pdflush_threads" no longer used */
{ CTL_INT, VM_OVERCOMMIT_RATIO, "overcommit_ratio" },
/* VM_PAGEBUF unused */
/* VM_HUGETLB_PAGES "nr_hugepages" no longer used */
diff -puN mm/backing-dev.c~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads mm/backing-dev.c
--- a/mm/backing-dev.c~mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads
+++ a/mm/backing-dev.c
@@ -886,3 +886,23 @@ out:
return ret;
}
EXPORT_SYMBOL(wait_iff_congested);
+
+int pdflush_proc_obsolete(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ char kbuf[] = "0\n";
+
+ if (*ppos) {
+ *lenp = 0;
+ return 0;
+ }
+
+ if (copy_to_user(buffer, kbuf, sizeof(kbuf)))
+ return -EFAULT;
+ printk_once(KERN_WARNING "%s exported in /proc is scheduled for removal\n",
+ table->procname);
+
+ *lenp = 2;
+ *ppos += *lenp;
+ return 2;
+}
_
Subject: Subject: mm: prepare for removal of obsolete /proc/sys/vm/nr_pdflush_threads
Patches currently in -mm which might be from liwp@xxxxxxxxxxxxxxxxxx are
mm-prepare-for-removal-of-obsolete-proc-sys-vm-nr_pdflush_threads.patch
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