linux-ext4 - [RFC PATCH 1/1] fs: jbd2: try to launch cp transaction when bh refer cma

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <20240820072609.570513-1-zhaoyang.huang@unisoc.com>
Date: Tue, 20 Aug 2024 15:26:09 +0800
From: "zhaoyang.huang" <zhaoyang.huang@...soc.com>
To: "Theodore Ts'o" <tytso@....edu>, Jan Kara <jack@...e.com>,
        <linux-fsdevel@...r.kernel.org>, <linux-ext4@...r.kernel.org>,
        Zhaoyang Huang
	<huangzhaoyang@...il.com>, <steve.kang@...soc.com>
Subject: [RFC PATCH 1/1] fs: jbd2: try to launch cp transaction when bh refer cma

From: Zhaoyang Huang <zhaoyang.huang@...soc.com>

cma_alloc() keep failed when an bunch of IO operations happened on an
journal enabled ext4 device which is caused by a jh->bh->b_page
can not be migrated out of CMA area as the jh has one cp_transaction
pending on it. We solve this by launching jbd2_log_do_checkpoint forcefully
somewhere. Since journal is common mechanism to all JFSs and
cp_transaction has a little fewer opportunity to be launched, this patch
would like to introduce a timing point at which the
cp_transaction->t_checkpoint_list is shrunk if CMA page used for
journalling.

Signed-off-by: Zhaoyang Huang <zhaoyang.huang@...soc.com>
---
 fs/jbd2/checkpoint.c | 27 +++++++++++++++++++++++++++
 fs/jbd2/journal.c    |  4 ++++
 include/linux/jbd2.h |  2 ++
 3 files changed, 33 insertions(+)

diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c
index 951f78634adf..8c6c1dba1f0f 100644
--- a/fs/jbd2/checkpoint.c
+++ b/fs/jbd2/checkpoint.c
@@ -21,6 +21,7 @@
 #include <linux/slab.h>
 #include <linux/blkdev.h>
 #include <trace/events/jbd2.h>
+#include <linux/mm.h>
 
 /*
  * Unlink a buffer from a transaction checkpoint list.
@@ -137,6 +138,32 @@ __flush_batch(journal_t *journal, int *batch_count)
 	*batch_count = 0;
 }
 
+#ifdef CONFIG_CMA
+void drain_cma_bh(journal_t *journal)
+{
+	struct journal_head	*jh;
+	struct buffer_head	*bh;
+
+	if (!journal->j_checkpoint_transactions)
+		return;
+
+	jh = journal->j_checkpoint_transactions->t_checkpoint_list;
+	while (jh) {
+		bh = jh2bh(jh);
+
+		if (bh && get_pageblock_migratetype(bh->b_page) == MIGRATE_CMA) {
+			mutex_lock_io(&journal->j_checkpoint_mutex);
+			jbd2_log_do_checkpoint(journal);
+			mutex_unlock(&journal->j_checkpoint_mutex);
+			return;
+		}
+
+		jh = jh->b_cpnext;
+	}
+}
+#else
+void drain_cma_bh(journal_t *journal) {}
+#endif
 /*
  * Perform an actual checkpoint. We take the first transaction on the
  * list of transactions to be checkpointed and send all its buffers
diff --git a/fs/jbd2/journal.c b/fs/jbd2/journal.c
index 1ebf2393bfb7..dd92cb7404fc 100644
--- a/fs/jbd2/journal.c
+++ b/fs/jbd2/journal.c
@@ -41,6 +41,7 @@
 #include <linux/bitops.h>
 #include <linux/ratelimit.h>
 #include <linux/sched/mm.h>
+#include <linux/swap.h>
 
 #define CREATE_TRACE_POINTS
 #include <trace/events/jbd2.h>
@@ -1273,6 +1274,9 @@ static unsigned long jbd2_journal_shrink_scan(struct shrinker *shrink,
 	count = percpu_counter_read_positive(&journal->j_checkpoint_jh_count);
 	trace_jbd2_shrink_scan_enter(journal, sc->nr_to_scan, count);
 
+	if (current_is_kswapd())
+		drain_cma_bh(journal);
+
 	nr_shrunk = jbd2_journal_shrink_checkpoint_list(journal, &nr_to_scan);
 
 	count = percpu_counter_read_positive(&journal->j_checkpoint_jh_count);
diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 5157d92b6f23..fc152382a6ae 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -105,6 +105,8 @@ typedef struct jbd2_journal_handle handle_t;	/* Atomic operation type */
 typedef struct journal_s	journal_t;	/* Journal control structure */
 #endif
 
+void drain_cma_bh(journal_t *journal);
+
 /*
  * Internal structures used by the logging mechanism:
  */
-- 
2.25.1