linux-kernel - [PATCH] pstore/zone: Use GFP_ATOMIC to allocate zone buffer

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Message-ID: <CAJRQjofRCF7wjrYmw3D7zd5QZnwHQq+F8U-mJDJ6NZ4bddYdLA@mail.gmail.com>
Date:   Sun, 4 Sep 2022 23:17:13 +0800
From:   Qiujun Huang <hqjagain@...il.com>
To:     keescook@...omium.org, anton@...msg.org, ccross@...roid.com,
        tony.luck@...el.com, LKML <linux-kernel@...r.kernel.org>
Subject: [PATCH] pstore/zone: Use GFP_ATOMIC to allocate zone buffer

There is a case found when triggering a panic_on_oom, pstore fails to dump
kmsg. Because psz_kmsg_write_record can't get the new buffer.

Handle this by using GFP_ATOMIC to allocate a buffer at lower watermark.

Signed-off-by: Qiujun Huang <hqjagain@...il.com>
---
 fs/pstore/zone.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/fs/pstore/zone.c b/fs/pstore/zone.c
index 017d0d4ad329..2770746bb7aa 100644
--- a/fs/pstore/zone.c
+++ b/fs/pstore/zone.c
@@ -761,7 +761,7 @@ static inline int notrace
psz_kmsg_write_record(struct psz_context *cxt,
  /* avoid destroying old data, allocate a new one */
  len = zone->buffer_size + sizeof(*zone->buffer);
  zone->oldbuf = zone->buffer;
- zone->buffer = kzalloc(len, GFP_KERNEL);
+ zone->buffer = kzalloc(len, GFP_ATOMIC);
  if (!zone->buffer) {
  zone->buffer = zone->oldbuf;
  return -ENOMEM;
-- 
2.25.1