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@kakra kakra commented Dec 5, 2021

Add the following flags to give an hint about which chunk should be
allocated in which a disk.
The following flags are created:

- BTRFS_DEV_ALLOCATION_PREFERRED_DATA
  preferred data chunk, but metadata chunk allowed
- BTRFS_DEV_ALLOCATION_PREFERRED_METADATA
  preferred metadata chunk, but data chunk allowed
- BTRFS_DEV_ALLOCATION_METADATA_ONLY
  only metadata chunk allowed
- BTRFS_DEV_ALLOCATION_DATA_ONLY
  only data chunk allowed

Signed-off-by: Goffredo Baroncelli <[email protected]>
When this mode is enabled, the chunk allocation policy is modified as
follow.

Each disk may have a different tag:
- BTRFS_DEV_ALLOCATION_PREFERRED_METADATA
- BTRFS_DEV_ALLOCATION_METADATA_ONLY
- BTRFS_DEV_ALLOCATION_DATA_ONLY
- BTRFS_DEV_ALLOCATION_PREFERRED_DATA (default)

Where:
- ALLOCATION_PREFERRED_X means that it is preferred to use this disk for
the X chunk type (the other type may be allowed when the space is low)
- ALLOCATION_X_ONLY means that it is used *only* for the X chunk type.
This means also that it is a preferred choice.

Each time the allocator allocates a chunk of type X , first it takes the
disks tagged as ALLOCATION_X_ONLY or ALLOCATION_PREFERRED_X; if the space
is not enough, it uses also the disks tagged as ALLOCATION_METADATA_ONLY;
if the space is not enough, it uses also the other disks, with the
exception of the one marked as ALLOCATION_PREFERRED_Y, where Y the other
type of chunk (i.e. not X).

Signed-off-by: Goffredo Baroncelli <[email protected]>
@kakra kakra added the done To be superseded by next LTS label Dec 18, 2022
@kakra kakra closed this Mar 11, 2023
kakra pushed a commit that referenced this pull request Sep 9, 2024
[ Upstream commit 3b65644 ]

The RISC-V kernel already has checks to ensure that memory which would
lie outside of the linear mapping is not used. However those checks
use memory_limit, which is used to implement the mem= kernel command
line option (to limit the total amount of memory, not its address
range). When memory is made up of two or more non-contiguous memory
banks this check is incorrect.

Two changes are made here:
 - add a call in setup_bootmem() to memblock_cap_memory_range() which
   will cause any memory which falls outside the linear mapping to be
   removed from the memory regions.
 - remove the check in create_linear_mapping_page_table() which was
   intended to remove memory which is outside the liner mapping based
   on memory_limit, as it is no longer needed. Note a check for
   mapping more memory than memory_limit (to implement mem=) is
   unnecessary because of the existing call to
   memblock_enforce_memory_limit().

This issue was seen when booting on a SV39 platform with two memory
banks:
  0x00,80000000 1GiB
  0x20,00000000 32GiB
This memory range is 158GiB from top to bottom, but the linear mapping
is limited to 128GiB, so the lower block of RAM will be mapped at
PAGE_OFFSET, and the upper block straddles the top of the linear
mapping.

This causes the following Oops:
[    0.000000] Linux version 6.10.0-rc2-gd3b8dd5b51dd-dirty ([email protected]) (riscv64-codasip-linux-gcc (GCC) 13.2.0, GNU ld (GNU Binutils) 2.41.0.20231213) #20 SMP Sat Jun 22 11:34:22 BST 2024
[    0.000000] memblock_add: [0x0000000080000000-0x00000000bfffffff] early_init_dt_add_memory_arch+0x4a/0x52
[    0.000000] memblock_add: [0x0000002000000000-0x00000027ffffffff] early_init_dt_add_memory_arch+0x4a/0x52
...
[    0.000000] memblock_alloc_try_nid: 23724 bytes align=0x8 nid=-1 from=0x0000000000000000 max_addr=0x0000000000000000 early_init_dt_alloc_memory_arch+0x1e/0x48
[    0.000000] memblock_reserve: [0x00000027ffff5350-0x00000027ffffaffb] memblock_alloc_range_nid+0xb8/0x132
[    0.000000] Unable to handle kernel paging request at virtual address fffffffe7fff5350
[    0.000000] Oops [#1]
[    0.000000] Modules linked in:
[    0.000000] CPU: 0 PID: 0 Comm: swapper Not tainted 6.10.0-rc2-gd3b8dd5b51dd-dirty #20
[    0.000000] Hardware name: codasip,a70x (DT)
[    0.000000] epc : __memset+0x8c/0x104
[    0.000000]  ra : memblock_alloc_try_nid+0x74/0x84
[    0.000000] epc : ffffffff805e88c8 ra : ffffffff806148f6 sp : ffffffff80e03d50
[    0.000000]  gp : ffffffff80ec4158 tp : ffffffff80e0bec0 t0 : fffffffe7fff52f8
[    0.000000]  t1 : 00000027ffffb000 t2 : 5f6b636f6c626d65 s0 : ffffffff80e03d90
[    0.000000]  s1 : 0000000000005cac a0 : fffffffe7fff5350 a1 : 0000000000000000
[    0.000000]  a2 : 0000000000005cac a3 : fffffffe7fffaff8 a4 : 000000000000002c
[    0.000000]  a5 : ffffffff805e88c8 a6 : 0000000000005cac a7 : 0000000000000030
[    0.000000]  s2 : fffffffe7fff5350 s3 : ffffffffffffffff s4 : 0000000000000000
[    0.000000]  s5 : ffffffff8062347e s6 : 0000000000000000 s7 : 0000000000000001
[    0.000000]  s8 : 0000000000002000 s9 : 00000000800226d0 s10: 0000000000000000
[    0.000000]  s11: 0000000000000000 t3 : ffffffff8080a928 t4 : ffffffff8080a928
[    0.000000]  t5 : ffffffff8080a928 t6 : ffffffff8080a940
[    0.000000] status: 0000000200000100 badaddr: fffffffe7fff5350 cause: 000000000000000f
[    0.000000] [<ffffffff805e88c8>] __memset+0x8c/0x104
[    0.000000] [<ffffffff8062349c>] early_init_dt_alloc_memory_arch+0x1e/0x48
[    0.000000] [<ffffffff8043e892>] __unflatten_device_tree+0x52/0x114
[    0.000000] [<ffffffff8062441e>] unflatten_device_tree+0x9e/0xb8
[    0.000000] [<ffffffff806046fe>] setup_arch+0xd4/0x5bc
[    0.000000] [<ffffffff806007aa>] start_kernel+0x76/0x81a
[    0.000000] Code: b823 02b2 bc23 02b2 b023 04b2 b423 04b2 b823 04b2 (bc23) 04b2
[    0.000000] ---[ end trace 0000000000000000 ]---
[    0.000000] Kernel panic - not syncing: Attempted to kill the idle task!
[    0.000000] ---[ end Kernel panic - not syncing: Attempted to kill the idle task! ]---

The problem is that memblock (unaware that some physical memory cannot
be used) has allocated memory from the top of memory but which is
outside the linear mapping region.

Signed-off-by: Stuart Menefy <[email protected]>
Fixes: c99127c ("riscv: Make sure the linear mapping does not use the kernel mapping")
Reviewed-by: David McKay <[email protected]>
Reviewed-by: Alexandre Ghiti <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Palmer Dabbelt <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
kakra pushed a commit that referenced this pull request Sep 9, 2024
[ Upstream commit db19d3a ]

There is a race condition in the CMT interrupt handler. In the interrupt
handler the driver sets a driver private flag, FLAG_IRQCONTEXT. This
flag is used to indicate any call to set_next_event() should not be
directly propagated to the device, but instead cached. This is done as
the interrupt handler itself reprograms the device when needed before it
completes and this avoids this operation to take place twice.

It is unclear why this design was chosen, my suspicion is to allow the
struct clock_event_device.event_handler callback, which is called while
the FLAG_IRQCONTEXT is set, can update the next event without having to
write to the device twice.

Unfortunately there is a race between when the FLAG_IRQCONTEXT flag is
set and later cleared where the interrupt handler have already started to
write the next event to the device. If set_next_event() is called in
this window the value is only cached in the driver but not written. This
leads to the board to misbehave, or worse lockup and produce a splat.

   rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
   rcu:     0-...!: (0 ticks this GP) idle=f5e0/0/0x0 softirq=519/519 fqs=0 (false positive?)
   rcu:     (detected by 1, t=6502 jiffies, g=-595, q=77 ncpus=2)
   Sending NMI from CPU 1 to CPUs 0:
   NMI backtrace for cpu 0
   CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.10.0-rc5-arm64-renesas-00019-g74a6f86eaf1c-dirty #20
   Hardware name: Renesas Salvator-X 2nd version board based on r8a77965 (DT)
   pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
   pc : tick_check_broadcast_expired+0xc/0x40
   lr : cpu_idle_poll.isra.0+0x8c/0x168
   sp : ffff800081c63d70
   x29: ffff800081c63d70 x28: 00000000580000c8 x27: 00000000bfee5610
   x26: 0000000000000027 x25: 0000000000000000 x24: 0000000000000000
   x23: ffff00007fbb9100 x22: ffff8000818f1008 x21: ffff8000800ef07c
   x20: ffff800081c79ec0 x19: ffff800081c70c28 x18: 0000000000000000
   x17: 0000000000000000 x16: 0000000000000000 x15: 0000ffffc2c717d8
   x14: 0000000000000000 x13: ffff000009c18080 x12: ffff8000825f7fc0
   x11: 0000000000000000 x10: ffff8000818f3cd4 x9 : 0000000000000028
   x8 : ffff800081c79ec0 x7 : ffff800081c73000 x6 : 0000000000000000
   x5 : 0000000000000000 x4 : ffff7ffffe286000 x3 : 0000000000000000
   x2 : ffff7ffffe286000 x1 : ffff800082972900 x0 : ffff8000818f1008
   Call trace:
    tick_check_broadcast_expired+0xc/0x40
    do_idle+0x9c/0x280
    cpu_startup_entry+0x34/0x40
    kernel_init+0x0/0x11c
    do_one_initcall+0x0/0x260
    __primary_switched+0x80/0x88
   rcu: rcu_preempt kthread timer wakeup didn't happen for 6501 jiffies! g-595 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402
   rcu:     Possible timer handling issue on cpu=0 timer-softirq=262
   rcu: rcu_preempt kthread starved for 6502 jiffies! g-595 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x402 ->cpu=0
   rcu:     Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior.
   rcu: RCU grace-period kthread stack dump:
   task:rcu_preempt     state:I stack:0     pid:15    tgid:15    ppid:2      flags:0x00000008
   Call trace:
    __switch_to+0xbc/0x100
    __schedule+0x358/0xbe0
    schedule+0x48/0x148
    schedule_timeout+0xc4/0x138
    rcu_gp_fqs_loop+0x12c/0x764
    rcu_gp_kthread+0x208/0x298
    kthread+0x10c/0x110
    ret_from_fork+0x10/0x20

The design have been part of the driver since it was first merged in
early 2009. It becomes increasingly harder to trigger the issue the
older kernel version one tries. It only takes a few boots on v6.10-rc5,
while hundreds of boots are needed to trigger it on v5.10.

Close the race condition by using the CMT channel lock for the two
competing sections. The channel lock was added to the driver after its
initial design.

Signed-off-by: Niklas Söderlund <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Daniel Lezcano <[email protected]>
Signed-off-by: Sasha Levin <[email protected]>
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