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smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=N2s6fsjR; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="N2s6fsjR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5207F1F00A3A; Fri, 3 Jul 2026 18:03:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1783101801; bh=Lay32htZlqrllyOYStYXibcI4UNRnS4xy3opZawI3yQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=N2s6fsjRDa2ItCEaC9c+nar6pcelED4QaEQKw95lHUjvYhZcSzvyhfhXdhnvAoEPt TIkyIQ9Ob9Ct1cSBVvm/8pyKVKO+N0SbQpSCgQTuXCoTeWeMGLke9qCyqytBWhzDy+ S4vIuLadkenLHTHvDPNJ5qYSb24/jWTVldDB93ZRBUBVDTy7NsTu7OOWkbw6Fh4oP9 ZRN4Z7PpEuesWMe+Ckl8BKJoOINAWKtcizRASv6qVjGXjCgl9eaRCb+uFwol6Wi6xj JwqKFZb1eVDrmEdYqAvD6MoEIxXM7LH2MpdOf0DXpgIwhYl1GNRMdoIBRiaCcGAKI1 vyfBxvKaChDeg== From: Sasha Levin To: stable@vger.kernel.org Cc: Chao Yu , stable@kernel.org, Ruipeng Qi , Chao Yu , Jaegeuk Kim , Sasha Levin Subject: [PATCH 6.18.y 2/2] f2fs: fix potential deadlock in gc_merge path of f2fs_balance_fs() Date: Fri, 3 Jul 2026 14:03:17 -0400 Message-ID: <20260703180317.196634-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260703180317.196634-1-sashal@kernel.org> References: <2026070241-banker-throwback-07c2@gregkh> <20260703180317.196634-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Chao Yu [ Upstream commit 8b4468ec023d0d1b4669dfb867588997cc03a06b ] When we mount device w/ gc_merge mount option, we may suffer below potential deadlock: Kworker GC trehad Truncator - f2fs_write_cache_pages - f2fs_write_single_data_page - f2fs_do_write_data_page - folio_start_writeback --- set writeback flag on folio - f2fs_outplace_write_data : cached folio in internal bio cache - f2fs_balance_fs - wake_up(gc_thread) : wake up gc thread to run foreground GC - finish_wait(fggc_wq) : wait on the waitqueue --- wait on GC thread to finish the work - truncate_inode_pages_range - __filemap_get_folio(, FGP_LOCK) --- lock folio - truncate_inode_partial_folio - folio_wait_writeback --- wait on writeback being cleared - do_garbage_collect - move_data_page - f2fs_get_lock_data_folio - lock on folio --- blocked on folio's lock In order to avoid such deadlock, let's call below functions to commit cached bios in GC_MERGE path of f2fs_balance_fs() as the same as we did in NOGC_MERGE path. - f2fs_submit_merged_write(sbi, DATA); - f2fs_submit_all_merged_ipu_writes(sbi); Cc: stable@kernel.org Fixes: 351df4b20115 ("f2fs: add segment operations") Cc: Ruipeng Qi Reported: Sandeep Dhavale Signed-off-by: Chao Yu Signed-off-by: Chao Yu Signed-off-by: Jaegeuk Kim Signed-off-by: Sasha Levin --- fs/f2fs/segment.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/fs/f2fs/segment.c b/fs/f2fs/segment.c index 7acfb52a5fa131..0a080cb55c414b 100644 --- a/fs/f2fs/segment.c +++ b/fs/f2fs/segment.c @@ -443,6 +443,13 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need) if (has_enough_free_secs(sbi, 0, 0)) return; + /* + * Submit all cached OPU/IPU DATA bios before triggering + * foreground GC to avoid potential deadlocks. + */ + f2fs_submit_merged_write(sbi, DATA); + f2fs_submit_all_merged_ipu_writes(sbi); + if (test_opt(sbi, GC_MERGE) && sbi->gc_thread && sbi->gc_thread->f2fs_gc_task) { DEFINE_WAIT(wait); @@ -462,13 +469,6 @@ void f2fs_balance_fs(struct f2fs_sb_info *sbi, bool need) .err_gc_skipped = false, .nr_free_secs = 1 }; - /* - * Submit all cached OPU/IPU DATA bios before triggering - * foreground GC to avoid potential deadlocks. - */ - f2fs_submit_merged_write(sbi, DATA); - f2fs_submit_all_merged_ipu_writes(sbi); - f2fs_down_write(&sbi->gc_lock); stat_inc_gc_call_count(sbi, FOREGROUND); f2fs_gc(sbi, &gc_control); -- 2.53.0