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![Chao Yu](/assets/img/avatar_default.png)
As Jia-Ju Bai reported: "According to fs/f2fs/trace.c, the kernel module may sleep under a spinlock. The function call path is: f2fs_trace_pid (acquire the spinlock) f2fs_radix_tree_insert cond_resched --> may sleep I do not find a good way to fix it, so I only report. This possible bug is found by my static analysis tool (DSAC) and my code review." Obviously, it's problemetic to schedule in critical region of spinlock, which will cause uninterruptable sleep if there is no waker. This patch changes to use mutex lock intead of spinlock to avoid this condition. Reported-by: Jia-Ju Bai <baijiaju1990@gmail.com> Signed-off-by: Chao Yu <yuchao0@huawei.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
162 lines
3.5 KiB
C
162 lines
3.5 KiB
C
/*
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* f2fs IO tracer
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*
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* Copyright (c) 2014 Motorola Mobility
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* Copyright (c) 2014 Jaegeuk Kim <jaegeuk@kernel.org>
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#include <linux/fs.h>
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#include <linux/f2fs_fs.h>
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#include <linux/sched.h>
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#include <linux/radix-tree.h>
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#include "f2fs.h"
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#include "trace.h"
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static RADIX_TREE(pids, GFP_ATOMIC);
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static struct mutex pids_lock;
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static struct last_io_info last_io;
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static inline void __print_last_io(void)
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{
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if (!last_io.len)
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return;
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trace_printk("%3x:%3x %4x %-16s %2x %5x %5x %12x %4x\n",
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last_io.major, last_io.minor,
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last_io.pid, "----------------",
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last_io.type,
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last_io.fio.op, last_io.fio.op_flags,
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last_io.fio.new_blkaddr,
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last_io.len);
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memset(&last_io, 0, sizeof(last_io));
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}
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static int __file_type(struct inode *inode, pid_t pid)
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{
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if (f2fs_is_atomic_file(inode))
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return __ATOMIC_FILE;
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else if (f2fs_is_volatile_file(inode))
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return __VOLATILE_FILE;
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else if (S_ISDIR(inode->i_mode))
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return __DIR_FILE;
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else if (inode->i_ino == F2FS_NODE_INO(F2FS_I_SB(inode)))
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return __NODE_FILE;
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else if (inode->i_ino == F2FS_META_INO(F2FS_I_SB(inode)))
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return __META_FILE;
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else if (pid)
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return __NORMAL_FILE;
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else
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return __MISC_FILE;
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}
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void f2fs_trace_pid(struct page *page)
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{
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struct inode *inode = page->mapping->host;
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pid_t pid = task_pid_nr(current);
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void *p;
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set_page_private(page, (unsigned long)pid);
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if (radix_tree_preload(GFP_NOFS))
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return;
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mutex_lock(&pids_lock);
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p = radix_tree_lookup(&pids, pid);
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if (p == current)
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goto out;
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if (p)
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radix_tree_delete(&pids, pid);
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f2fs_radix_tree_insert(&pids, pid, current);
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trace_printk("%3x:%3x %4x %-16s\n",
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MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev),
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pid, current->comm);
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out:
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mutex_unlock(&pids_lock);
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radix_tree_preload_end();
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}
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void f2fs_trace_ios(struct f2fs_io_info *fio, int flush)
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{
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struct inode *inode;
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pid_t pid;
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int major, minor;
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if (flush) {
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__print_last_io();
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return;
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}
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inode = fio->page->mapping->host;
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pid = page_private(fio->page);
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major = MAJOR(inode->i_sb->s_dev);
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minor = MINOR(inode->i_sb->s_dev);
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if (last_io.major == major && last_io.minor == minor &&
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last_io.pid == pid &&
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last_io.type == __file_type(inode, pid) &&
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last_io.fio.op == fio->op &&
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last_io.fio.op_flags == fio->op_flags &&
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last_io.fio.new_blkaddr + last_io.len ==
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fio->new_blkaddr) {
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last_io.len++;
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return;
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}
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__print_last_io();
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last_io.major = major;
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last_io.minor = minor;
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last_io.pid = pid;
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last_io.type = __file_type(inode, pid);
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last_io.fio = *fio;
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last_io.len = 1;
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return;
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}
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void f2fs_build_trace_ios(void)
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{
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mutex_init(&pids_lock);
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}
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#define PIDVEC_SIZE 128
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static unsigned int gang_lookup_pids(pid_t *results, unsigned long first_index,
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unsigned int max_items)
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{
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struct radix_tree_iter iter;
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void **slot;
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unsigned int ret = 0;
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if (unlikely(!max_items))
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return 0;
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radix_tree_for_each_slot(slot, &pids, &iter, first_index) {
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results[ret] = iter.index;
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if (++ret == max_items)
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break;
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}
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return ret;
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}
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void f2fs_destroy_trace_ios(void)
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{
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pid_t pid[PIDVEC_SIZE];
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pid_t next_pid = 0;
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unsigned int found;
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mutex_lock(&pids_lock);
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while ((found = gang_lookup_pids(pid, next_pid, PIDVEC_SIZE))) {
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unsigned idx;
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next_pid = pid[found - 1] + 1;
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for (idx = 0; idx < found; idx++)
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radix_tree_delete(&pids, pid[idx]);
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}
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mutex_unlock(&pids_lock);
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}
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