On 2019/2/4 16:06, Sahitya Tummala wrote:
> Fix below warning coming because of using mutex lock in atomic context.
>
> BUG: sleeping function called from invalid context at
> kernel/locking/mutex.c:98
> in_atomic(): 1, irqs_disabled(): 0, pid: 585, name: sh
> Preemption disabled at: __radix_tree_preload+0x28/0x130
> Call trace:
> dump_backtrace+0x0/0x2b4
> show_stack+0x20/0x28
> dump_stack+0xa8/0xe0
> ___might_sleep+0x144/0x194
> __might_sleep+0x58/0x8c
> mutex_lock+0x2c/0x48
> f2fs_trace_pid+0x88/0x14c
> f2fs_set_node_page_dirty+0xd0/0x184
>
> Do not use f2fs_radix_tree_insert() to avoid doing cond_resched() with
> spin_lock() acquired.
>
> Signed-off-by: Sahitya Tummala <stumm...@codeaurora.org>
> ---
> fs/f2fs/trace.c | 20 +++++++++++++-------
> 1 file changed, 13 insertions(+), 7 deletions(-)
>
> diff --git a/fs/f2fs/trace.c b/fs/f2fs/trace.c
> index ce2a5eb..d0ab533 100644
> --- a/fs/f2fs/trace.c
> +++ b/fs/f2fs/trace.c
> @@ -14,7 +14,7 @@
> #include "trace.h"
>
> static RADIX_TREE(pids, GFP_ATOMIC);
> -static struct mutex pids_lock;
> +static spinlock_t pids_lock;
> static struct last_io_info last_io;
>
> static inline void __print_last_io(void)
> @@ -58,23 +58,29 @@ void f2fs_trace_pid(struct page *page)
>
> set_page_private(page, (unsigned long)pid);
>
> +retry:
> if (radix_tree_preload(GFP_NOFS))
> return;
>
> - mutex_lock(&pids_lock);
> + spin_lock(&pids_lock);
> p = radix_tree_lookup(&pids, pid);
> if (p == current)
> goto out;
> if (p)
> radix_tree_delete(&pids, pid);
>
> - f2fs_radix_tree_insert(&pids, pid, current);
> + if (radix_tree_insert(&pids, pid, current)) {
> + spin_unlock(&pids_lock);
> + radix_tree_preload_end();
> + cond_resched();
> + goto retry;
> + }
>
> trace_printk("%3x:%3x %4x %-16s\n",
> MAJOR(inode->i_sb->s_dev), MINOR(inode->i_sb->s_dev),
> pid, current->comm);
Hi Sahitya,
Can trace_printk sleep? For safety, how about moving it out of spinlock?
Thanks,
> out:
> - mutex_unlock(&pids_lock);
> + spin_unlock(&pids_lock);
> radix_tree_preload_end();
> }
>
> @@ -119,7 +125,7 @@ void f2fs_trace_ios(struct f2fs_io_info *fio, int flush)
>
> void f2fs_build_trace_ios(void)
> {
> - mutex_init(&pids_lock);
> + spin_lock_init(&pids_lock);
> }
>
> #define PIDVEC_SIZE 128
> @@ -147,7 +153,7 @@ void f2fs_destroy_trace_ios(void)
> pid_t next_pid = 0;
> unsigned int found;
>
> - mutex_lock(&pids_lock);
> + spin_lock(&pids_lock);
> while ((found = gang_lookup_pids(pid, next_pid, PIDVEC_SIZE))) {
> unsigned idx;
>
> @@ -155,5 +161,5 @@ void f2fs_destroy_trace_ios(void)
> for (idx = 0; idx < found; idx++)
> radix_tree_delete(&pids, pid[idx]);
> }
> - mutex_unlock(&pids_lock);
> + spin_unlock(&pids_lock);
> }
>
