From ec8d823eb0493b0bf85f81719fa04e2b00a0daaa Mon Sep 17 00:00:00 2001 From: Jialin Wang Date: Fri, 8 Aug 2025 00:54:55 +0800 Subject: [PATCH] proc: proc_maps_open allow proc_mem_open to return NULL commit c0e1b774f68bdbea1618e356e30672c7f1e32509 upstream. The commit 65c66047259f ("proc: fix the issue of proc_mem_open returning NULL") caused proc_maps_open() to return -ESRCH when proc_mem_open() returns NULL. This breaks legitimate /proc//maps access for kernel threads since kernel threads have NULL mm_struct. The regression causes perf to fail and exit when profiling a kernel thread: # perf record -v -g -p $(pgrep kswapd0) ... couldn't open /proc/65/task/65/maps This patch partially reverts the commit to fix it. Link: https://lkml.kernel.org/r/20250807165455.73656-1-wjl.linux@gmail.com Fixes: 65c66047259f ("proc: fix the issue of proc_mem_open returning NULL") Signed-off-by: Jialin Wang Cc: Penglei Jiang Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman --- fs/proc/task_mmu.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c index 0102ab3aaec16..bdc3c2e9334ad 100644 --- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c @@ -212,8 +212,8 @@ static int proc_maps_open(struct inode *inode, struct file *file, priv->inode = inode; priv->mm = proc_mem_open(inode, PTRACE_MODE_READ); - if (IS_ERR_OR_NULL(priv->mm)) { - int err = priv->mm ? PTR_ERR(priv->mm) : -ESRCH; + if (IS_ERR(priv->mm)) { + int err = PTR_ERR(priv->mm); seq_release_private(inode, file); return err; -- 2.47.3