From fd38b75c4b43295b10d69772a46d1c74dbd6fc81 Mon Sep 17 00:00:00 2001 From: Usama Arif Date: Tue, 16 Jun 2026 07:15:17 -0700 Subject: [PATCH] kernel/fork: clear PF_BLOCK_TS in copy_process() PF_BLOCK_TS is only set in blk_time_get_ns() when current->plug is non-NULL, and blk_finish_plug() clears it via __blk_flush_plug() before NULLing the plug pointer. copy_process() breaks the invariant by inheriting PF_BLOCK_TS from the parent while resetting the child's plug to NULL. Clear PF_BLOCK_TS alongside that assignment so callers can rely on "PF_BLOCK_TS set implies current->plug != NULL" and dereference current->plug unguarded. Fixes: 06b23f92af87 ("block: update cached timestamp post schedule/preemption") Cc: stable@vger.kernel.org Signed-off-by: Usama Arif Link: https://patch.msgid.link/20260616141604.328820-2-usama.arif@linux.dev Signed-off-by: Jens Axboe --- kernel/fork.c | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/fork.c b/kernel/fork.c index addc555a1077..1fafcb9bb047 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -2337,6 +2337,7 @@ __latent_entropy struct task_struct *copy_process( #ifdef CONFIG_BLOCK p->plug = NULL; + p->flags &= ~PF_BLOCK_TS; #endif futex_init_task(p);