[PATCH 2/2] userfaultfd: Set the corresponding flag in IOU worker context

Zhiwei Jiang
2025-04-22T10:46:19Z

Set this to avoid premature return from schedule in IOU worker threads,
ensuring it sleeps and waits to be woken up as in normal cases.

Signed-off-by: Zhiwei Jiang <qq282012236@gmail.com>
---
fs/userfaultfd.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
index d80f94346199..74bead069e85 100644
--- a/fs/userfaultfd.c
+++ b/fs/userfaultfd.c
@@ -32,6 +32,7 @@
#include <linux/swapops.h>
#include <linux/miscdevice.h>
#include <linux/uio.h>
+#include "../io_uring/io-wq.h"

static int sysctl_unprivileged_userfaultfd __read_mostly;

@@ -369,7 +370,10 @@ vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason)
vm_fault_t ret = VM_FAULT_SIGBUS;
bool must_wait;
unsigned int blocking_state;
+ struct io_worker *worker = current->worker_private;

+ if (worker)
+ set_userfault_flag_for_ioworker(worker);
/*
* We don't do userfault handling for the final child pid update
* and when coredumping (faults triggered by get_dump_page()).
@@ -506,6 +510,9 @@ vm_fault_t handle_userfault(struct vm_fault *vmf, unsigned long reason)

__set_current_state(TASK_RUNNING);

+ if (worker)
+ clear_userfault_flag_for_ioworker(worker);
+
/*
* Here we race with the list_del; list_add in
* userfaultfd_ctx_read(), however because we don't ever run
--
2.34.1