Hi Liam,
On Wed, Sep 6, 2023 at 5:24 PM Liam R. Howlett Liam.Howlett@oracle.com wrote:
- Geert Uytterhoeven geert@linux-m68k.org [230829 12:42]:
On Fri, 18 Aug 2023, Liam R. Howlett wrote:
The current implementation of append may cause duplicate data and/or incorrect ranges to be returned to a reader during an update. Although this has not been reported or seen, disable the append write operation while the tree is in rcu mode out of an abundance of caution.
...
Fixes: 54a611b60590 ("Maple Tree: add new data structure") Cc: stable@vger.kernel.org Signed-off-by: Liam R. Howlett Liam.Howlett@oracle.com
Thanks for your patch, which is now commit cfeb6ae8bcb96ccf ("maple_tree: disable mas_wr_append() when other readers are possible") in v6.5, and is being backported to stable.
On Renesas RZ/A1 and RZ/A2 (single-core Cortex-A9), this causes the following warning:
clocksource: timer@e803b000: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 28958491609 ns sched_clock: 32 bits at 66MHz, resolution 15ns, wraps every 32537631224ns /soc/timer@e803b000: used for clocksource /soc/timer@e803c000: used for clock events +------------[ cut here ]------------ +WARNING: CPU: 0 PID: 0 at init/main.c:992 start_kernel+0x2f0/0x480 +Interrupts were enabled earlyNote that the maple tree is involved in tracking the interrupts, see kernel/irq/irqdesc.c irq_insert_desc(), etc.
+CPU: 0 PID: 0 Comm: swapper Not tainted 6.5.0-rza2mevb-10197-g99b80d6b92b5 #237I cannot find commit id 99b80d6b92b5.
That's my local tree, based on renesas-drivers-2023-08-29-v6.5.
+Hardware name: Generic R7S9210 (Flattened Device Tree) + unwind_backtrace from show_stack+0x10/0x14 + show_stack from dump_stack_lvl+0x24/0x3c + dump_stack_lvl from __warn+0x74/0xb8 + __warn from warn_slowpath_fmt+0x78/0xb0 + warn_slowpath_fmt from start_kernel+0x2f0/0x480 + start_kernel from 0x0 +---[ end trace 0000000000000000 ]--- Console: colour dummy device 80x30 printk: console [tty0] enabled Calibrating delay loop (skipped) preset value.. 1056.00 BogoMIPS (lpj=5280000)Reverting this commit fixes the issue.
I have set up testing with qemu for powerpc 32b, and reverting this patch does not fix it for me. Did you revert the patch or bisect to the issue?
I did bisect the issue (on RZ/A) to cfeb6ae8bcb96ccf. Reverting that commit on top of my local tree fixed the issue.
It also happens on 0e0e9bd5f7b9 (I ran git checkout cfeb6ae8bcb96ccf^ to get the commit immediately before cfeb6ae8bcb96ccf).
That is not the case on Renesas RZ/A (which is arm32).
Gr{oetje,eeting}s,
Geert