Fixes for 6.6

Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/queue-6.6/blk-iocost-fix-an-ubsan-shift-out-of-bounds-warning.patch b/queue-6.6/blk-iocost-fix-an-ubsan-shift-out-of-bounds-warning.patch
new file mode 100644 (file)
index 0000000..7939493
--- /dev/null
+++ b/queue-6.6/blk-iocost-fix-an-ubsan-shift-out-of-bounds-warning.patch
@@ -0,0 +1,72 @@
+From 3a8c1b84a21d24dc2d845fedb9ee6d586ffad105 Mon Sep 17 00:00:00 2001
+From: Sasha Levin <sashal@kernel.org>
+Date: Mon, 20 Nov 2023 12:25:56 -1000
+Subject: blk-iocost: Fix an UBSAN shift-out-of-bounds warning
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+From: Tejun Heo <tj@kernel.org>
+
+[ Upstream commit 2a427b49d02995ea4a6ff93a1432c40fa4d36821 ]
+
+When iocg_kick_delay() is called from a CPU different than the one which set
+the delay, @now may be in the past of @iocg->delay_at leading to the
+following warning:
+
+  UBSAN: shift-out-of-bounds in block/blk-iocost.c:1359:23
+  shift exponent 18446744073709 is too large for 64-bit type 'u64' (aka 'unsigned long long')
+  ...
+  Call Trace:
+   <TASK>
+   dump_stack_lvl+0x79/0xc0
+   __ubsan_handle_shift_out_of_bounds+0x2ab/0x300
+   iocg_kick_delay+0x222/0x230
+   ioc_rqos_merge+0x1d7/0x2c0
+   __rq_qos_merge+0x2c/0x80
+   bio_attempt_back_merge+0x83/0x190
+   blk_attempt_plug_merge+0x101/0x150
+   blk_mq_submit_bio+0x2b1/0x720
+   submit_bio_noacct_nocheck+0x320/0x3e0
+   __swap_writepage+0x2ab/0x9d0
+
+The underflow itself doesn't really affect the behavior in any meaningful
+way; however, the past timestamp may exaggerate the delay amount calculated
+later in the code, which shouldn't be a material problem given the nature of
+the delay mechanism.
+
+If @now is in the past, this CPU is racing another CPU which recently set up
+the delay and there's nothing this CPU can contribute w.r.t. the delay.
+Let's bail early from iocg_kick_delay() in such cases.
+
+Reported-by: Breno Leitão <leitao@debian.org>
+Signed-off-by: Tejun Heo <tj@kernel.org>
+Fixes: 5160a5a53c0c ("blk-iocost: implement delay adjustment hysteresis")
+Link: https://lore.kernel.org/r/ZVvc9L_CYk5LO1fT@slm.duckdns.org
+Signed-off-by: Jens Axboe <axboe@kernel.dk>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ block/blk-iocost.c | 7 +++++++
+ 1 file changed, 7 insertions(+)
+
+diff --git a/block/blk-iocost.c b/block/blk-iocost.c
+index 089fcb9cfce3..7ee8d85c2c68 100644
+--- a/block/blk-iocost.c
++++ b/block/blk-iocost.c
+@@ -1353,6 +1353,13 @@ static bool iocg_kick_delay(struct ioc_gq *iocg, struct ioc_now *now)
+ 
+       lockdep_assert_held(&iocg->waitq.lock);
+ 
++      /*
++       * If the delay is set by another CPU, we may be in the past. No need to
++       * change anything if so. This avoids decay calculation underflow.
++       */
++      if (time_before64(now->now, iocg->delay_at))
++              return false;
++
+       /* calculate the current delay in effect - 1/2 every second */
+       tdelta = now->now - iocg->delay_at;
+       if (iocg->delay)
+-- 
+2.43.0
+

diff --git a/queue-6.6/series b/queue-6.6/series
index 46afaee0ef07ce63e0448fdabaf1e31f5c2428dc..d8ff713254e72b87d42b1c5bec8721f098f86261 100644 (file)
--- a/queue-6.6/series
+++ b/queue-6.6/series
@@ -95,3 +95,4 @@ libceph-rename-read_sparse_msg_-to-read_partial_spar.patch
 libceph-just-wait-for-more-data-to-be-available-on-t.patch
 riscv-fix-arch_hugetlb_migration_supported-for-napot.patch
 riscv-declare-overflow_stack-as-exported-from-traps..patch
+blk-iocost-fix-an-ubsan-shift-out-of-bounds-warning.patch