shutdown_mem_profiling() calls remove_proc_entry() from
reserve_module_tags(), which runs under mod_lock held for write.
remove_proc_entry() waits for readers, and a reader takes mod_lock for
read in allocinfo_start():
CPU0 (insmod) CPU1 (read /proc/allocinfo)
---------------- ----------------------------
reserve_module_tags()
down_write(&mod_lock) [held]
use_pde() [in_use++]
allocinfo_start()
down_read(&mod_lock) <- blocks
shutdown_mem_profiling()
remove_proc_entry()
wait for in_use == 0 <- blocks
Move remove_proc_entry() to a workqueue.
Fixes: 4835f747d3ed ("alloc_tag: support for page allocation tag compression")
Signed-off-by: Hao Ge <[email protected]>
---
mm/alloc_tag.c | 9 ++++++++-
1 file changed, 8 insertions(+), 1 deletion(-)
diff --git a/mm/alloc_tag.c b/mm/alloc_tag.c
index 7481180dadd2..b80f5a151f28 100644
--- a/mm/alloc_tag.c
+++ b/mm/alloc_tag.c
@@ -591,6 +591,13 @@ void pgalloc_tag_swap(struct folio *new, struct folio *old)
put_page_tag_ref(handle_new);
}
+static void remove_allocinfo_file(struct work_struct *work)
+{
+ remove_proc_entry(ALLOCINFO_FILE_NAME, NULL);
+}
+
+static DECLARE_WORK(remove_allocinfo_work, remove_allocinfo_file);
+
static void shutdown_mem_profiling(bool remove_file)
{
if (mem_alloc_profiling_enabled())
@@ -600,7 +607,7 @@ static void shutdown_mem_profiling(bool remove_file)
return;
if (remove_file)
- remove_proc_entry(ALLOCINFO_FILE_NAME, NULL);
+ schedule_work(&remove_allocinfo_work);
mem_profiling_support = false;
}
--
2.25.1
