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@linux.vnet.ibm.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>
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@ -0,0 +1,5 @@
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What: /proc/sys/vm/nr_pdflush_threads
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Date: June 2012
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Contact: Wanpeng Li <liwp@linux.vnet.ibm.com>
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Description: Since pdflush is replaced by per-BDI flusher, the interface of old pdflush
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exported in /proc/sys/vm/ should be removed.
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@ -13,6 +13,14 @@ Who: Jim Cromie <jim.cromie@gmail.com>, Jason Baron <jbaron@redhat.com>
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---------------------------
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---------------------------
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What: /proc/sys/vm/nr_pdflush_threads
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When: 2012
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Why: Since pdflush is deprecated, the interface exported in /proc/sys/vm/
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should be removed.
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Who: Wanpeng Li <liwp@linux.vnet.ibm.com>
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---------------------------
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What: CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
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What: CONFIG_APM_CPU_IDLE, and its ability to call APM BIOS in idle
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When: 2012
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When: 2012
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Why: This optional sub-feature of APM is of dubious reliability,
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Why: This optional sub-feature of APM is of dubious reliability,
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@ -42,7 +42,6 @@ Currently, these files are in /proc/sys/vm:
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- mmap_min_addr
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- mmap_min_addr
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- nr_hugepages
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- nr_hugepages
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- nr_overcommit_hugepages
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- nr_overcommit_hugepages
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- nr_pdflush_threads
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- nr_trim_pages (only if CONFIG_MMU=n)
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- nr_trim_pages (only if CONFIG_MMU=n)
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- numa_zonelist_order
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- numa_zonelist_order
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- oom_dump_tasks
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- oom_dump_tasks
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@ -426,16 +425,6 @@ See Documentation/vm/hugetlbpage.txt
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==============================================================
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==============================================================
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nr_pdflush_threads
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The current number of pdflush threads. This value is read-only.
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The value changes according to the number of dirty pages in the system.
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When necessary, additional pdflush threads are created, one per second, up to
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nr_pdflush_threads_max.
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==============================================================
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nr_trim_pages
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nr_trim_pages
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This is available only on NOMMU kernels.
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This is available only on NOMMU kernels.
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@ -52,11 +52,6 @@ struct wb_writeback_work {
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struct completion *done; /* set if the caller waits */
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struct completion *done; /* set if the caller waits */
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};
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};
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/*
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* We don't actually have pdflush, but this one is exported though /proc...
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*/
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int nr_pdflush_threads;
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/**
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/**
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* writeback_in_progress - determine whether there is writeback in progress
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* writeback_in_progress - determine whether there is writeback in progress
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* @bdi: the device's backing_dev_info structure.
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* @bdi: the device's backing_dev_info structure.
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@ -17,6 +17,7 @@
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#include <linux/timer.h>
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#include <linux/timer.h>
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#include <linux/writeback.h>
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#include <linux/writeback.h>
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#include <linux/atomic.h>
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#include <linux/atomic.h>
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#include <linux/sysctl.h>
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struct page;
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struct page;
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struct device;
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struct device;
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@ -304,6 +305,8 @@ void clear_bdi_congested(struct backing_dev_info *bdi, int sync);
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void set_bdi_congested(struct backing_dev_info *bdi, int sync);
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void set_bdi_congested(struct backing_dev_info *bdi, int sync);
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long congestion_wait(int sync, long timeout);
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long congestion_wait(int sync, long timeout);
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long wait_iff_congested(struct zone *zone, int sync, long timeout);
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long wait_iff_congested(struct zone *zone, int sync, long timeout);
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int pdflush_proc_obsolete(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos);
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static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
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static inline bool bdi_cap_writeback_dirty(struct backing_dev_info *bdi)
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{
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{
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@ -189,9 +189,4 @@ void tag_pages_for_writeback(struct address_space *mapping,
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void account_page_redirty(struct page *page);
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void account_page_redirty(struct page *page);
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/* pdflush.c */
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extern int nr_pdflush_threads; /* Global so it can be exported to sysctl
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read-only. */
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#endif /* WRITEBACK_H */
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#endif /* WRITEBACK_H */
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@ -1101,11 +1101,9 @@ static struct ctl_table vm_table[] = {
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.extra1 = &zero,
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.extra1 = &zero,
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},
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},
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{
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{
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.procname = "nr_pdflush_threads",
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.procname = "nr_pdflush_threads",
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.data = &nr_pdflush_threads,
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.mode = 0444 /* read-only */,
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.maxlen = sizeof nr_pdflush_threads,
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.proc_handler = pdflush_proc_obsolete,
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.mode = 0444 /* read-only*/,
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.proc_handler = proc_dointvec,
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},
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},
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{
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{
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.procname = "swappiness",
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.procname = "swappiness",
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@ -147,7 +147,7 @@ static const struct bin_table bin_vm_table[] = {
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{ CTL_INT, VM_DIRTY_RATIO, "dirty_ratio" },
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{ CTL_INT, VM_DIRTY_RATIO, "dirty_ratio" },
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/* VM_DIRTY_WB_CS "dirty_writeback_centisecs" no longer used */
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/* VM_DIRTY_WB_CS "dirty_writeback_centisecs" no longer used */
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/* VM_DIRTY_EXPIRE_CS "dirty_expire_centisecs" no longer used */
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/* VM_DIRTY_EXPIRE_CS "dirty_expire_centisecs" no longer used */
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{ CTL_INT, VM_NR_PDFLUSH_THREADS, "nr_pdflush_threads" },
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/* VM_NR_PDFLUSH_THREADS "nr_pdflush_threads" no longer used */
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{ CTL_INT, VM_OVERCOMMIT_RATIO, "overcommit_ratio" },
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{ CTL_INT, VM_OVERCOMMIT_RATIO, "overcommit_ratio" },
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/* VM_PAGEBUF unused */
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/* VM_PAGEBUF unused */
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/* VM_HUGETLB_PAGES "nr_hugepages" no longer used */
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/* VM_HUGETLB_PAGES "nr_hugepages" no longer used */
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@ -886,3 +886,23 @@ out:
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return ret;
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return ret;
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}
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}
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EXPORT_SYMBOL(wait_iff_congested);
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EXPORT_SYMBOL(wait_iff_congested);
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int pdflush_proc_obsolete(struct ctl_table *table, int write,
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void __user *buffer, size_t *lenp, loff_t *ppos)
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{
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char kbuf[] = "0\n";
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if (*ppos) {
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*lenp = 0;
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return 0;
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}
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if (copy_to_user(buffer, kbuf, sizeof(kbuf)))
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return -EFAULT;
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printk_once(KERN_WARNING "%s exported in /proc is scheduled for removal\n",
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table->procname);
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*lenp = 2;
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*ppos += *lenp;
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return 2;
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}
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