Attached is a patch against 2.4.0-test1-ac10 which adds a VM pressure
callback list, and cleans up the notifier chain code in the process.
Since the callback occurs in do_try_to_free_pages, it is rather low
level, giving other kernel code flexibility when it comes to freeing
memory. Kernel code wishing to handle memory pressure should call
register_freemem_notifier. Thanks for the suggestions Andi. Goodnight
all. :)
-- Jeff Garzik | Liberty is always dangerous, but Building 1024 | it is the safest thing we have. MandrakeSoft, Inc. | -- Harry Emerson Fosdick
diff -ur vanilla/linux-2.4.0-test1-ac10/mm/vmscan.c linux_2_3/mm/vmscan.c --- vanilla/linux-2.4.0-test1-ac10/mm/vmscan.c Tue Jun 6 14:44:31 2000 +++ linux_2_3/mm/vmscan.c Wed Jun 7 06:14:32 2000 @@ -23,6 +23,9 @@ #include <asm/pgalloc.h> +/* list of funcs to call when memory pressure occurs */ +extern struct notifier_block *freemem_notifier_list; + /* * The swap-out functions return 1 if they successfully * threw something out, and we got a free page. It returns @@ -428,6 +431,29 @@ } /* + * The freemem notifier list holds a list of functions + * that are to be called when trying to free pages. + * + * Call them... We don't use notifier_call_chain + * because the return code from a freemem notifier + * is treated as a shrink_*_memory-style return value. + */ +static int shrink_misc_memory (int priority, unsigned int gfp_mask) +{ + int count = 0; + struct notifier_block *nb = freemem_notifier_list; + + while (nb) { + count += nb->notifier_call(nb, + (unsigned long) priority, + (void *)(unsigned long) gfp_mask); + nb = nb->next; + } + + return count; +} + +/* * We need to make the locks finer granularity, but right * now we need this so that we can do page allocations * without holding the kernel lock etc. @@ -475,6 +501,20 @@ ret = 1; if (!--count) goto done; + } + } + + /* + * Call everybody who registered a mem pressure notifier. + * + * If freemem_notifier_list will usually be non-NULL + * during normal system operation, remove the non-NULL test. + */ + if (freemem_notifier_list != NULL) { + count -= shrink_misc_memory(priority, gfp_mask); + if (count <= 0) { + ret = 1; + goto done; } } diff -ur vanilla/linux-2.4.0-test1-ac10/include/linux/mm.h linux_2_3/include/linux/mm.h --- vanilla/linux-2.4.0-test1-ac10/include/linux/mm.h Tue Jun 6 14:44:30 2000 +++ linux_2_3/include/linux/mm.h Wed Jun 7 06:14:31 2000 @@ -10,6 +10,7 @@ #include <linux/string.h> #include <linux/list.h> #include <linux/mmzone.h> +#include <linux/notifier.h> extern unsigned long max_mapnr; extern unsigned long num_physpages; @@ -415,6 +416,9 @@ extern int access_process_vm(struct task_struct *tsk, unsigned long addr, void *buf, int len, int write); extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char *dst, int len); extern int ptrace_writedata(struct task_struct *tsk, char * src, unsigned long dst, int len); + +extern int register_freemem_notifier(struct notifier_block *); +extern int unregister_freemem_notifier(struct notifier_block *); extern int pgt_cache_water[2]; extern int check_pgt_cache(void); diff -ur vanilla/linux-2.4.0-test1-ac10/include/linux/notifier.h linux_2_3/include/linux/notifier.h --- vanilla/linux-2.4.0-test1-ac10/include/linux/notifier.h Thu Mar 30 10:03:49 2000 +++ linux_2_3/include/linux/notifier.h Wed Jun 7 06:14:32 2000 @@ -21,62 +21,15 @@ #ifdef __KERNEL__ +extern int notifier_chain_register(struct notifier_block **list, struct notifier_block *n); +extern int notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n); +extern int notifier_call_chain(struct notifier_block **n, unsigned long val, void *v); + #define NOTIFY_DONE 0x0000 /* Don't care */ #define NOTIFY_OK 0x0001 /* Suits me */ #define NOTIFY_STOP_MASK 0x8000 /* Don't call further */ #define NOTIFY_BAD (NOTIFY_STOP_MASK|0x0002) /* Bad/Veto action */ -extern __inline__ int notifier_chain_register(struct notifier_block **list, struct notifier_block *n) -{ - while(*list) - { - if(n->priority > (*list)->priority) - break; - list= &((*list)->next); - } - n->next = *list; - *list=n; - return 0; -} - -/* - * Warning to any non GPL module writers out there.. these functions are - * GPL'd - */ - -extern __inline__ int notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n) -{ - while((*nl)!=NULL) - { - if((*nl)==n) - { - *nl=n->next; - return 0; - } - nl=&((*nl)->next); - } - return -ENOENT; -} - -/* - * This is one of these things that is generally shorter inline - */ - -extern __inline__ int notifier_call_chain(struct notifier_block **n, unsigned long val, void *v) -{ - int ret=NOTIFY_DONE; - struct notifier_block *nb = *n; - while(nb) - { - ret=nb->notifier_call(nb,val,v); - if(ret&NOTIFY_STOP_MASK) - return ret; - nb=nb->next; - } - return ret; -} - - /* * Declared notifiers so far. I can imagine quite a few more chains * over time (eg laptop power reset chains, reboot chain (to clean @@ -105,11 +58,5 @@ #define SYS_HALT 0x0002 /* Notify of system halt */ #define SYS_POWER_OFF 0x0003 /* Notify of system power off */ -/* - * Publically visible notifier objects - */ - -extern struct notifier_block *boot_notifier_list; - -#endif -#endif +#endif /* __KERNEL__ */ +#endif /* _LINUX_NOTIFIER_H */ diff -ur vanilla/linux-2.4.0-test1-ac10/kernel/Makefile linux_2_3/kernel/Makefile --- vanilla/linux-2.4.0-test1-ac10/kernel/Makefile Wed Mar 22 12:39:11 2000 +++ linux_2_3/kernel/Makefile Wed Jun 7 06:14:32 2000 @@ -8,11 +8,11 @@ # Note 2! The CFLAGS definitions are now in the main makefile... O_TARGET := kernel.o -O_OBJS = sched.o dma.o fork.o exec_domain.o panic.o printk.o sys.o \ +O_OBJS = sched.o dma.o fork.o exec_domain.o panic.o printk.o \ module.o exit.o itimer.o info.o time.o softirq.o resource.o \ sysctl.o acct.o capability.o ptrace.o timer.o -OX_OBJS += signal.o +OX_OBJS += signal.o sys.o ifeq ($(CONFIG_UID16),y) O_OBJS += uid16.o diff -ur vanilla/linux-2.4.0-test1-ac10/kernel/ksyms.c linux_2_3/kernel/ksyms.c --- vanilla/linux-2.4.0-test1-ac10/kernel/ksyms.c Tue Jun 6 14:44:31 2000 +++ linux_2_3/kernel/ksyms.c Wed Jun 7 06:14:32 2000 @@ -129,7 +129,6 @@ /* filesystem internal functions */ EXPORT_SYMBOL(def_blk_fops); -EXPORT_SYMBOL(in_group_p); EXPORT_SYMBOL(update_atime); EXPORT_SYMBOL(get_super); EXPORT_SYMBOL(get_empty_super); @@ -446,8 +445,6 @@ EXPORT_SYMBOL(machine_restart); EXPORT_SYMBOL(machine_halt); EXPORT_SYMBOL(machine_power_off); -EXPORT_SYMBOL(register_reboot_notifier); -EXPORT_SYMBOL(unregister_reboot_notifier); EXPORT_SYMBOL(_ctype); EXPORT_SYMBOL(secure_tcp_sequence_number); EXPORT_SYMBOL(get_random_bytes); diff -ur vanilla/linux-2.4.0-test1-ac10/kernel/sys.c linux_2_3/kernel/sys.c --- vanilla/linux-2.4.0-test1-ac10/kernel/sys.c Tue Jun 6 14:44:31 2000 +++ linux_2_3/kernel/sys.c Wed Jun 7 06:14:32 2000 @@ -4,6 +4,7 @@ * Copyright (C) 1991, 1992 Linus Torvalds */ +#include <linux/module.h> #include <linux/mm.h> #include <linux/utsname.h> #include <linux/mman.h> @@ -47,17 +48,160 @@ */ static struct notifier_block *reboot_notifier_list = NULL; +struct notifier_block *freemem_notifier_list = NULL; +static spinlock_t notifier_lock = SPIN_LOCK_UNLOCKED; +/** + * notifier_chain_register - Add notifier to a notifier chain + * @list: Pointer to root list pointer + * @n: New entry in notifier chain + * + * Adds a notifier to a notifier chain. + * + * Currently always returns zero. + */ + +int notifier_chain_register(struct notifier_block **list, struct notifier_block *n) +{ + spin_lock(¬ifier_lock); + while(*list) + { + if(n->priority > (*list)->priority) + break; + list= &((*list)->next); + } + n->next = *list; + *list=n; + spin_unlock(¬ifier_lock); + return 0; +} + +/** + * notifier_chain_unregister - Remove notifier from a notifier chain + * @nl: Pointer to root list pointer + * @n: New entry in notifier chain + * + * Removes a notifier from a notifier chain. + * + * Returns zero on success, or %-ENOENT on failure. + */ + +int notifier_chain_unregister(struct notifier_block **nl, struct notifier_block *n) +{ + spin_lock(¬ifier_lock); + while((*nl)!=NULL) + { + if((*nl)==n) + { + *nl=n->next; + spin_unlock(¬ifier_lock); + return 0; + } + nl=&((*nl)->next); + } + spin_unlock(¬ifier_lock); + return -ENOENT; +} + +/** + * notifier_call_chain - Call functions in a notifier chain + * @n: Pointer to root pointer of notifier chain + * @val: Value passed unmodified to notifier function + * @v: Pointer passed unmodified to notifier function + * + * Calls each function in a notifier chain in turn. + * + * If the return value of the notifier can be and'd + * with %NOTIFY_STOP_MASK, then notifier_call_chain + * will return immediately, with the return value of + * the notifier function which halted execution. + * Otherwise, the return value is the return value + * of the last notifier function called. + */ + +int notifier_call_chain(struct notifier_block **n, unsigned long val, void *v) +{ + int ret=NOTIFY_DONE; + struct notifier_block *nb = *n; + + spin_lock(¬ifier_lock); + while(nb) + { + ret=nb->notifier_call(nb,val,v); + if(ret&NOTIFY_STOP_MASK) + { + spin_unlock(¬ifier_lock); + return ret; + } + nb=nb->next; + } + spin_unlock(¬ifier_lock); + return ret; +} + +/** + * register_reboot_notifier - Register function to be called at reboot time + * @nb: Info about notifier function to be called + * + * Registers a function with the list of functions + * to be called at reboot time. + * + * Currently always returns zero, as notifier_chain_register + * always returns zero. + */ + int register_reboot_notifier(struct notifier_block * nb) { return notifier_chain_register(&reboot_notifier_list, nb); } +/** + * unregister_reboot_notifier - Unregister previously registered reboot notifier + * @nb: Hook to be unregistered + * + * Unregisters a previously registered reboot + * notifier function. + * + * Returns zero on success, or %-ENOENT on failure. + */ + int unregister_reboot_notifier(struct notifier_block * nb) { return notifier_chain_unregister(&reboot_notifier_list, nb); } +/** + * register_freemem_notifier - Register function to be called at memory pressure time + * @nb: Info about notifier function to be called + * + * Registers a function with the list of functions + * to be called whenever the system attempts to + * free some pages, prior to swapping out pages. + * + * Currently always returns zero, as notifier_chain_register + * always returns zero. + */ + +int register_freemem_notifier(struct notifier_block * nb) +{ + return notifier_chain_register(&freemem_notifier_list, nb); +} + +/** + * unregister_freemem_notifier - Unregister previously registered mem pressure notifier + * @nb: Hook to be unregistered + * + * Unregisters a previously registered mem pressure + * notifier function. + * + * Returns zero on success, or %-ENOENT on failure. + */ + +int unregister_freemem_notifier(struct notifier_block * nb) +{ + return notifier_chain_unregister(&freemem_notifier_list, nb); +} + asmlinkage long sys_ni_syscall(void) { return -ENOSYS; @@ -1102,3 +1246,12 @@ return error; } +EXPORT_SYMBOL(notifier_chain_register); +EXPORT_SYMBOL(notifier_chain_unregister); +EXPORT_SYMBOL(notifier_call_chain); +EXPORT_SYMBOL(register_reboot_notifier); +EXPORT_SYMBOL(unregister_reboot_notifier); +EXPORT_SYMBOL(register_freemem_notifier); +EXPORT_SYMBOL(unregister_freemem_notifier); +EXPORT_SYMBOL(in_group_p); +EXPORT_SYMBOL(in_egroup_p);
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This archive was generated by hypermail 2b29 : Wed Jun 07 2000 - 21:00:28 EST