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Fri, 20 Jun 2025 12:16:01 +0900 Received: from devron.myhome.or.jp (foobar@localhost [127.0.0.1]) by devron.myhome.or.jp (8.18.1/8.18.1/Debian-6) with ESMTPS id 55K3G0jf040331 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NOT); Fri, 20 Jun 2025 12:16:00 +0900 Received: (from hirofumi@localhost) by devron.myhome.or.jp (8.18.1/8.18.1/Submit) id 55K3FxZK040330; Fri, 20 Jun 2025 12:15:59 +0900 From: OGAWA Hirofumi To: Andrew Morton Cc: Li Chen , linux-kernel@vger.kernel.org Subject: Re: [PATCH V2] fs: fat: Prevent fsfuzzer from dominating the console In-Reply-To: <20250620020231.9292-1-me@linux.beauty> References: <20250620020231.9292-1-me@linux.beauty> Date: Fri, 20 Jun 2025 12:15:59 +0900 Message-ID: <87a563w1ao.fsf@mail.parknet.co.jp> User-Agent: Gnus/5.13 (Gnus v5.13) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain Li Chen writes: > From: Li Chen > > fsfuzzer may make many invalid access for FAT-fs and generate many kmsg > like "FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb)". > > For platforms & os that enables hardware serial device whose speed are > slow, this may cause softlockup easily. > > So let's ratelimit the error log. > > The log as below: > [11916.242560] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.254485] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.266388] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.278287] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.290180] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.302068] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.313962] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.325848] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.337732] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.349619] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.361505] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.373391] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.385272] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.397144] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.409025] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.420909] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.432791] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.444674] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.456558] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.468446] FAT-fs (loop2): error, invalid access to FAT (entry 0x00000ccb) > [11916.480352] watchdog: BUG: soft lockup - CPU#58 stuck for 26s! [cat:2446035] > [11916.480357] Modules linked in: ... > [11916.480503] CPU: 58 PID: 2446035 Comm: cat Kdump: loaded Tainted: ... > [11916.480508] Hardware name: vclusters VSFT5000 B/VSFT5000 B, BIOS ... > [11916.480510] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > [11916.480513] pc : console_emit_next_record+0x1b4/0x288 > [11916.480524] lr : console_emit_next_record+0x1ac/0x288 > [11916.480525] sp : ffff80009bcdae90 > [11916.480527] x29: ffff80009bcdaec0 x28: ffff800082513810 x27: 0000000000000001 > [11916.480530] x26: 0000000000000001 x25: ffff800081f66000 x24: 0000000000000000 > [11916.480533] x23: 0000000000000000 x22: ffff80009bcdaf8f x21: 0000000000000001 > [11916.480535] x20: 0000000000000000 x19: ffff800082513810 x18: ffffffffffffffff > [11916.480538] x17: 0000000000000002 x16: 0000000000000001 x15: ffff80009bcdab30 > [11916.480541] x14: 0000000000000000 x13: 205d353330363434 x12: 32545b5d36343438 > [11916.480543] x11: 652820544146206f x10: 7420737365636361 x9 : ffff800080159a6c > [11916.480546] x8 : 69202c726f727265 x7 : 545b5d3634343836 x6 : 342e36313931315b > [11916.480549] x5 : ffff800082513a01 x4 : ffff80009bcdad31 x3 : 0000000000000000 > [11916.480551] x2 : 00000000ffffffff x1 : 0000000001b9b000 x0 : ffff8000836cef00 > [11916.480554] Call trace: > [11916.480557] console_emit_next_record+0x1b4/0x288 > [11916.480560] console_flush_all+0xcc/0x190 > [11916.480563] console_unlock+0x78/0x138 > [11916.480565] vprintk_emit+0x1c4/0x210 > [11916.480568] vprintk_default+0x40/0x58 > [11916.480570] vprintk+0x84/0xc8 > [11916.480572] _printk+0x68/0xa0 > [11916.480578] _fat_msg+0x6c/0xa0 [fat] > [11916.480593] __fat_fs_error+0xf8/0x118 [fat] > [11916.480601] fat_ent_read+0x164/0x238 [fat] > [11916.480609] fat_get_cluster+0x180/0x2c8 [fat] > [11916.480617] fat_get_mapped_cluster+0xb8/0x170 [fat] > > Signed-off-by: Li Chen Looks good. Acked-by: OGAWA Hirofumi Thanks. > --- > Changelog: > v2: use fat_fs_error_ratelimit instead as suggested by OGAWA Hirofumi > > fs/fat/fatent.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/fat/fatent.c b/fs/fat/fatent.c > index 1db348f8f887a..a7061c2ad8e4d 100644 > --- a/fs/fat/fatent.c > +++ b/fs/fat/fatent.c > @@ -356,7 +356,7 @@ int fat_ent_read(struct inode *inode, struct fat_entry *fatent, int entry) > > if (!fat_valid_entry(sbi, entry)) { > fatent_brelse(fatent); > - fat_fs_error(sb, "invalid access to FAT (entry 0x%08x)", entry); > + fat_fs_error_ratelimit(sb, "invalid access to FAT (entry 0x%08x)", entry); > return -EIO; > } -- OGAWA Hirofumi