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Thu, 14 Feb 2019 07:46:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1550130394; bh=4UWOZAHo8P5HQluG58zpa1sMTmgdpcRHGQVkuLn1LPA=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=XhTDONbpT7oTsDWWBRzzBxU7ROS2IhorXaPvPhySTWE6tc9GEVRsU25V2cpFf6k+H cPmf0NJPqverwcXF8/xotYJs4MgH+9JbZr/687M7bTZ0w6NqtbnjivJzuFIIpcBVo+ 0tBNQxlPhG+cxI8V/eHA8Wrbw27CS3j5kNXt2Qsc= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org E2DDD605A0 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=stummala@codeaurora.org Date: Thu, 14 Feb 2019 13:16:28 +0530 From: Sahitya Tummala To: Chao Yu Cc: Jaegeuk Kim , linux-f2fs-devel@lists.sourceforge.net, linux-kernel@vger.kernel.org Subject: Re: [PATCH] f2fs: do not use mutex lock in atomic context Message-ID: <20190214074628.GD7308@codeaurora.org> References: <1549267613-9288-1-git-send-email-stummala@codeaurora.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 13, 2019 at 11:25:31AM +0800, Chao Yu wrote: > 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 > > --- > > 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? > Hi Chao, Yes, trace_printk() is safe to use in atomic context (unlike printk). Thanks, Sahitya. > 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); > > } > > > -- -- Sent by a consultant of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum.