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 Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** 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: 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 -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html