linux-kernel - [for-next][PATCH 3/3] trace/pid_list: Change gfp flags in pid_list_fill

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Message-ID: <20240716180635.200391428@goodmis.org>
Date: Tue, 16 Jul 2024 14:06:16 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: linux-kernel@...r.kernel.org
Cc: Masami Hiramatsu <mhiramat@...nel.org>,
 Mark Rutland <mark.rutland@....com>,
 Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 stable@...dmis.org,
 "levi.yun" <yeoreum.yun@....com>
Subject: [for-next][PATCH 3/3] trace/pid_list: Change gfp flags in pid_list_fill_irq()

From: "levi.yun" <yeoreum.yun@....com>

pid_list_fill_irq() runs via irq_work.
When CONFIG_PREEMPT_RT is disabled, it would run in irq_context.
so it shouldn't sleep while memory allocation.

Change gfp flags from GFP_KERNEL to GFP_NOWAIT to prevent sleep in
irq_work.

This change wouldn't impact functionality in practice because the worst-size
is 2K.

Cc: stable@...dmis.org
Fixes: 8d6e90983ade2 ("tracing: Create a sparse bitmask for pid filtering")
Link: https://lore.kernel.org/20240704150226.1359936-1-yeoreum.yun@arm.com
Acked-by: Masami Hiramatsu (Google) <mhiramat@...nel.org>
Signed-off-by: levi.yun <yeoreum.yun@....com>
Signed-off-by: Steven Rostedt (Google) <rostedt@...dmis.org>
---
 kernel/trace/pid_list.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/trace/pid_list.c b/kernel/trace/pid_list.c
index 19b271a12c99..4966e6bbdf6f 100644
--- a/kernel/trace/pid_list.c
+++ b/kernel/trace/pid_list.c
@@ -354,7 +354,7 @@ static void pid_list_refill_irq(struct irq_work *iwork)
 	while (upper_count-- > 0) {
 		union upper_chunk *chunk;
 
-		chunk = kzalloc(sizeof(*chunk), GFP_KERNEL);
+		chunk = kzalloc(sizeof(*chunk), GFP_NOWAIT);
 		if (!chunk)
 			break;
 		*upper_next = chunk;
@@ -365,7 +365,7 @@ static void pid_list_refill_irq(struct irq_work *iwork)
 	while (lower_count-- > 0) {
 		union lower_chunk *chunk;
 
-		chunk = kzalloc(sizeof(*chunk), GFP_KERNEL);
+		chunk = kzalloc(sizeof(*chunk), GFP_NOWAIT);
 		if (!chunk)
 			break;
 		*lower_next = chunk;
-- 
2.43.0