https://github.com/torvalds/linux
Revision f3eab7184ddcd4867cf42e3274ba24a66e1e093d authored by Steve Capper on 22 March 2015, 14:51:51 UTC, committed by Catalin Marinas on 24 March 2015, 18:02:55 UTC
this_cpu operations were implemented for arm64 in: 5284e1b arm64: xchg: Implement cmpxchg_double f97fc81 arm64: percpu: Implement this_cpu operations Unfortunately, it is possible for pre-emption to take place between address generation and data access. This can lead to cases where data is being manipulated by this_cpu for a different CPU than it was called on. Which effectively breaks the spec. This patch disables pre-emption for the this_cpu operations guaranteeing that address generation and data manipulation take place without a pre-emption in-between. Fixes: 5284e1b4bc8a ("arm64: xchg: Implement cmpxchg_double") Fixes: f97fc810798c ("arm64: percpu: Implement this_cpu operations") Reported-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Steve Capper <steve.capper@linaro.org> [catalin.marinas@arm.com: remove space after type cast] Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
1 parent e53f21b
Tip revision: f3eab7184ddcd4867cf42e3274ba24a66e1e093d authored by Steve Capper on 22 March 2015, 14:51:51 UTC
arm64: percpu: Make this_cpu accessors pre-empt safe
arm64: percpu: Make this_cpu accessors pre-empt safe
Tip revision: f3eab71
drop_caches.c
/*
* Implement the manual drop-all-pagecache function
*/
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include <linux/writeback.h>
#include <linux/sysctl.h>
#include <linux/gfp.h>
#include "internal.h"
/* A global variable is a bit ugly, but it keeps the code simple */
int sysctl_drop_caches;
static void drop_pagecache_sb(struct super_block *sb, void *unused)
{
struct inode *inode, *toput_inode = NULL;
spin_lock(&inode_sb_list_lock);
list_for_each_entry(inode, &sb->s_inodes, i_sb_list) {
spin_lock(&inode->i_lock);
if ((inode->i_state & (I_FREEING|I_WILL_FREE|I_NEW)) ||
(inode->i_mapping->nrpages == 0)) {
spin_unlock(&inode->i_lock);
continue;
}
__iget(inode);
spin_unlock(&inode->i_lock);
spin_unlock(&inode_sb_list_lock);
invalidate_mapping_pages(inode->i_mapping, 0, -1);
iput(toput_inode);
toput_inode = inode;
spin_lock(&inode_sb_list_lock);
}
spin_unlock(&inode_sb_list_lock);
iput(toput_inode);
}
int drop_caches_sysctl_handler(struct ctl_table *table, int write,
void __user *buffer, size_t *length, loff_t *ppos)
{
int ret;
ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
if (ret)
return ret;
if (write) {
static int stfu;
if (sysctl_drop_caches & 1) {
iterate_supers(drop_pagecache_sb, NULL);
count_vm_event(DROP_PAGECACHE);
}
if (sysctl_drop_caches & 2) {
drop_slab();
count_vm_event(DROP_SLAB);
}
if (!stfu) {
pr_info("%s (%d): drop_caches: %d\n",
current->comm, task_pid_nr(current),
sysctl_drop_caches);
}
stfu |= sysctl_drop_caches & 4;
}
return 0;
}
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