tcmu_flush_dcache_range() gets called with addresses from both kernel
linear space and vmalloc space, so virt_to_page() or vmalloc_to_page()
have to be used as appropriate to get the proper page struct. On x86_64
flush_dcache_page() is the default noop implementation, so this hasn't
been a problem there.
When tcmu_flush_dcache_range() is called with a vmalloc address on Arm64,
the result is a kernel panic with the following stack trace:
[ 448.873342] CPU: 0 PID: 34102 Comm: iscsi_trx Kdump: loaded
Not tainted 5.4.17-2011.3.2.1.el8uek.aarch64 #2
[ 448.876144] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
[ 448.878377] pstate: 80400005 (Nzcv daif +PAN -UAO)
[ 448.880182] pc : flush_dcache_page+0x18/0x60
[ 448.881888] lr : is_ring_space_avail+0x74/0x390 [target_core_user]
[ 448.883969] sp : ffff80001720fa70
[ 448.885450] x29: ffff80001720fa70 x28: 0000000000000000
[ 448.887348] x27: 0000000000010000 x26: ffff0003c4b88000
[ 448.889285] x25: 0000000000010000 x24: ffff800017da0000
[ 448.891166] x23: ffffffdfffe00000 x22: 0000000000000078
[ 448.893061] x21: 0000800017da0001 x20: 000000000000ffff
[ 448.894931] x19: ffffffffffe5f680 x18: 0000000000000000
[ 448.896826] x17: 0000000000000000 x16: 0000000000000000
[ 448.898704] x15: 0000000000000000 x14: 0000000000000000
[ 448.900562] x13: 0000000000000000 x12: 0000000000000000
[ 448.902403] x11: ffff0003d188e4d0 x10: 0000000000000030
[ 448.904230] x9 : 0000000000000000 x8 : ffff0003d4073f00
[ 448.906094] x7 : 00000000000013b0 x6 : 000000000000003f
[ 448.907911] x5 : 0000000000000040 x4 : ffff0003d16d6258
[ 448.909720] x3 : 0000000000010000 x2 : 0000000000000078
[ 448.911664] x1 : ffff0003d16d6228 x0 : ffff800009f43b1c
[ 448.913767] Call trace:
[ 448.914984] flush_dcache_page+0x18/0x60
[ 448.916518] is_ring_space_avail+0x74/0x390 [target_core_user]
[ 448.918450] queue_cmd_ring+0x228/0x700 [target_core_user]
[ 448.920318] tcmu_queue_cmd+0xd8/0x14c [target_core_user]
[ 448.922192] __target_execute_cmd+0x30/0x130 [target_core_mod]
[ 448.924170] target_execute_cmd+0x1a4/0x450 [target_core_mod]
[ 448.926212] transport_generic_new_cmd+0x1b8/0x3a0 [target_core_mod]
[ 448.928289] transport_handle_cdb_direct+0x50/0xb0 [target_core_mod]
[ 448.930368] iscsit_execute_cmd+0x2c0/0x360 [iscsi_target_mod]
[ 448.932347] iscsit_sequence_cmd+0xd8/0x1c8 [iscsi_target_mod]
[ 448.934313] iscsit_process_scsi_cmd+0xac/0xf8 [iscsi_target_mod]
[ 448.936479] iscsit_get_rx_pdu+0x450/0xd68 [iscsi_target_mod]
[ 448.938423] iscsi_target_rx_thread+0xc0/0x168 [iscsi_target_mod]
[ 448.940387] kthread+0x110/0x114
[ 448.941802] ret_from_fork+0x10/0x18
[ 448.943271] Code: f9000bf3 aa0003f3 aa1e03e0 d503201f (f9400260)
[ 448.945271] SMP: stopping secondary CPUs
Signed-off-by: Henry Willard <[email protected]>
---
drivers/target/target_core_user.c | 10 +++++++++-
1 file changed, 9 insertions(+), 1 deletion(-)
diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
index 560bfec933bc..7557c0630483 100644
--- a/drivers/target/target_core_user.c
+++ b/drivers/target/target_core_user.c
@@ -597,11 +597,19 @@ static inline void tcmu_flush_dcache_range(void *vaddr, size_t size)
{
unsigned long offset = offset_in_page(vaddr);
void *start = vaddr - offset;
+ struct page *pg;
size = round_up(size+offset, PAGE_SIZE);
while (size) {
- flush_dcache_page(virt_to_page(start));
+ if (virt_addr_valid(start))
+ pg = virt_to_page(start);
+ else if (is_vmalloc_addr(start))
+ pg = vmalloc_to_page(start);
+ else
+ break;
+
+ flush_dcache_page(pg);
start += PAGE_SIZE;
size -= PAGE_SIZE;
}
--
1.8.3.1
> On Jun 19, 2020, at 1:41 PM, Henry Willard <[email protected]> wrote:
>
> tcmu_flush_dcache_range() gets called with addresses from both kernel
> linear space and vmalloc space, so virt_to_page() or vmalloc_to_page()
> have to be used as appropriate to get the proper page struct. On x86_64
> flush_dcache_page() is the default noop implementation, so this hasn't
> been a problem there.
>
> When tcmu_flush_dcache_range() is called with a vmalloc address on Arm64,
> the result is a kernel panic with the following stack trace:
>
> [ 448.873342] CPU: 0 PID: 34102 Comm: iscsi_trx Kdump: loaded
> Not tainted 5.4.17-2011.3.2.1.el8uek.aarch64 #2
> [ 448.876144] Hardware name: QEMU KVM Virtual Machine, BIOS 0.0.0 02/06/2015
> [ 448.878377] pstate: 80400005 (Nzcv daif +PAN -UAO)
> [ 448.880182] pc : flush_dcache_page+0x18/0x60
> [ 448.881888] lr : is_ring_space_avail+0x74/0x390 [target_core_user]
> [ 448.883969] sp : ffff80001720fa70
> [ 448.885450] x29: ffff80001720fa70 x28: 0000000000000000
> [ 448.887348] x27: 0000000000010000 x26: ffff0003c4b88000
> [ 448.889285] x25: 0000000000010000 x24: ffff800017da0000
> [ 448.891166] x23: ffffffdfffe00000 x22: 0000000000000078
> [ 448.893061] x21: 0000800017da0001 x20: 000000000000ffff
> [ 448.894931] x19: ffffffffffe5f680 x18: 0000000000000000
> [ 448.896826] x17: 0000000000000000 x16: 0000000000000000
> [ 448.898704] x15: 0000000000000000 x14: 0000000000000000
> [ 448.900562] x13: 0000000000000000 x12: 0000000000000000
> [ 448.902403] x11: ffff0003d188e4d0 x10: 0000000000000030
> [ 448.904230] x9 : 0000000000000000 x8 : ffff0003d4073f00
> [ 448.906094] x7 : 00000000000013b0 x6 : 000000000000003f
> [ 448.907911] x5 : 0000000000000040 x4 : ffff0003d16d6258
> [ 448.909720] x3 : 0000000000010000 x2 : 0000000000000078
> [ 448.911664] x1 : ffff0003d16d6228 x0 : ffff800009f43b1c
> [ 448.913767] Call trace:
> [ 448.914984] flush_dcache_page+0x18/0x60
> [ 448.916518] is_ring_space_avail+0x74/0x390 [target_core_user]
> [ 448.918450] queue_cmd_ring+0x228/0x700 [target_core_user]
> [ 448.920318] tcmu_queue_cmd+0xd8/0x14c [target_core_user]
> [ 448.922192] __target_execute_cmd+0x30/0x130 [target_core_mod]
> [ 448.924170] target_execute_cmd+0x1a4/0x450 [target_core_mod]
> [ 448.926212] transport_generic_new_cmd+0x1b8/0x3a0 [target_core_mod]
> [ 448.928289] transport_handle_cdb_direct+0x50/0xb0 [target_core_mod]
> [ 448.930368] iscsit_execute_cmd+0x2c0/0x360 [iscsi_target_mod]
> [ 448.932347] iscsit_sequence_cmd+0xd8/0x1c8 [iscsi_target_mod]
> [ 448.934313] iscsit_process_scsi_cmd+0xac/0xf8 [iscsi_target_mod]
> [ 448.936479] iscsit_get_rx_pdu+0x450/0xd68 [iscsi_target_mod]
> [ 448.938423] iscsi_target_rx_thread+0xc0/0x168 [iscsi_target_mod]
> [ 448.940387] kthread+0x110/0x114
> [ 448.941802] ret_from_fork+0x10/0x18
> [ 448.943271] Code: f9000bf3 aa0003f3 aa1e03e0 d503201f (f9400260)
> [ 448.945271] SMP: stopping secondary CPUs
>
> Signed-off-by: Henry Willard <[email protected]>
> ---
> drivers/target/target_core_user.c | 10 +++++++++-
> 1 file changed, 9 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/target/target_core_user.c b/drivers/target/target_core_user.c
> index 560bfec933bc..7557c0630483 100644
> --- a/drivers/target/target_core_user.c
> +++ b/drivers/target/target_core_user.c
> @@ -597,11 +597,19 @@ static inline void tcmu_flush_dcache_range(void *vaddr, size_t size)
> {
> unsigned long offset = offset_in_page(vaddr);
> void *start = vaddr - offset;
> + struct page *pg;
>
> size = round_up(size+offset, PAGE_SIZE);
>
> while (size) {
> - flush_dcache_page(virt_to_page(start));
> + if (virt_addr_valid(start))
> + pg = virt_to_page(start);
> + else if (is_vmalloc_addr(start))
> + pg = vmalloc_to_page(start);
> + else
> + break;
> +
> + flush_dcache_page(pg);
> start += PAGE_SIZE;
This was just fixed by Bodo:
https://lore.kernel.org/linux-scsi/[email protected]/
Hi Henry,
Thank you for the patch! Perhaps something to improve:
[auto build test WARNING on mkp-scsi/for-next]
[also build test WARNING on scsi/for-next v5.8-rc1 next-20200618]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use as documented in
https://git-scm.com/docs/git-format-patch]
url: https://github.com/0day-ci/linux/commits/Henry-Willard/scsi-target-tcmu-Call-flush_dcache_page-with-proper-page-struct/20200620-024740
base: https://git.kernel.org/pub/scm/linux/kernel/git/mkp/scsi.git for-next
config: xtensa-allyesconfig (attached as .config)
compiler: xtensa-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
chmod +x ~/bin/make.cross
# save the attached .config to linux build tree
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=xtensa
If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <[email protected]>
All warnings (new ones prefixed by >>, old ones prefixed by <<):
In file included from include/linux/kernel.h:11,
from include/linux/list.h:9,
from include/linux/preempt.h:11,
from include/linux/spinlock.h:51,
from drivers/target/target_core_user.c:9:
include/linux/scatterlist.h: In function 'sg_set_buf':
arch/xtensa/include/asm/page.h:193:9: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
193 | ((pfn) >= ARCH_PFN_OFFSET && ((pfn) - ARCH_PFN_OFFSET) < max_mapnr)
| ^~
include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
78 | # define unlikely(x) __builtin_expect(!!(x), 0)
| ^
include/linux/scatterlist.h:143:2: note: in expansion of macro 'BUG_ON'
143 | BUG_ON(!virt_addr_valid(buf));
| ^~~~~~
arch/xtensa/include/asm/page.h:201:32: note: in expansion of macro 'pfn_valid'
201 | #define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
| ^~~~~~~~~
include/linux/scatterlist.h:143:10: note: in expansion of macro 'virt_addr_valid'
143 | BUG_ON(!virt_addr_valid(buf));
| ^~~~~~~~~~~~~~~
In file included from ./arch/xtensa/include/generated/asm/bug.h:1,
from include/linux/bug.h:5,
from include/linux/thread_info.h:12,
from include/asm-generic/preempt.h:5,
from ./arch/xtensa/include/generated/asm/preempt.h:1,
from include/linux/preempt.h:78,
from include/linux/spinlock.h:51,
from drivers/target/target_core_user.c:9:
include/linux/dma-mapping.h: In function 'dma_map_resource':
arch/xtensa/include/asm/page.h:193:9: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
193 | ((pfn) >= ARCH_PFN_OFFSET && ((pfn) - ARCH_PFN_OFFSET) < max_mapnr)
| ^~
include/asm-generic/bug.h:144:27: note: in definition of macro 'WARN_ON_ONCE'
144 | int __ret_warn_once = !!(condition); | ^~~~~~~~~
include/linux/dma-mapping.h:352:19: note: in expansion of macro 'pfn_valid'
352 | if (WARN_ON_ONCE(pfn_valid(PHYS_PFN(phys_addr))))
| ^~~~~~~~~
In file included from include/linux/mm_types_task.h:16,
from include/linux/mm_types.h:5,
from include/linux/mmzone.h:21,
from include/linux/gfp.h:6,
from include/linux/umh.h:4,
from include/linux/kmod.h:9,
from include/linux/module.h:16,
from drivers/target/target_core_user.c:10:
drivers/target/target_core_user.c: In function 'tcmu_flush_dcache_range':
arch/xtensa/include/asm/page.h:193:9: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
193 | ((pfn) >= ARCH_PFN_OFFSET && ((pfn) - ARCH_PFN_OFFSET) < max_mapnr)
| ^~
arch/xtensa/include/asm/page.h:201:32: note: in expansion of macro 'pfn_valid'
201 | #define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
| ^~~~~~~~~
drivers/target/target_core_user.c:605:7: note: in expansion of macro 'virt_addr_valid'
605 | if (virt_addr_valid(start))
| ^~~~~~~~~~~~~~~
>> drivers/target/target_core_user.c:600:15: warning: variable 'pg' set but not used [-Wunused-but-set-variable]
600 | struct page *pg;
| ^~
vim +/pg +600 drivers/target/target_core_user.c
595
596 static inline void tcmu_flush_dcache_range(void *vaddr, size_t size)
597 {
598 unsigned long offset = offset_in_page(vaddr);
599 void *start = vaddr - offset;
> 600 struct page *pg;
601
602 size = round_up(size+offset, PAGE_SIZE);
603
604 while (size) {
605 if (virt_addr_valid(start))
606 pg = virt_to_page(start);
607 else if (is_vmalloc_addr(start))
608 pg = vmalloc_to_page(start);
609 else
610 break;
611
612 flush_dcache_page(pg);
613 start += PAGE_SIZE;
614 size -= PAGE_SIZE;
615 }
616 }
617
---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/[email protected]
On 6/19/20 6:31 PM, kernel test robot wrote:
> Hi Henry,
>
> Thank you for the patch! Perhaps something to improve:
>
> [auto build test WARNING on mkp-scsi/for-next]
> [also build test WARNING on scsi/for-next v5.8-rc1 next-20200618]
> [If your patch is applied to the wrong git tree, kindly drop us a note.
> And when submitting patch, we suggest to use as documented in
> https://git-scm.com/docs/git-format-patch]
>
> url: https://github.com/0day-ci/linux/commits/Henry-Willard/scsi-target-tcmu-Call-flush_dcache_page-with-proper-page-struct/20200620-024740
> base: https://git.kernel.org/pub/scm/linux/kernel/git/mkp/scsi.git for-next
> config: xtensa-allyesconfig (attached as .config)
> compiler: xtensa-linux-gcc (GCC) 9.3.0
> reproduce (this is a W=1 build):
> wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
> chmod +x ~/bin/make.cross
> # save the attached .config to linux build tree
> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=xtensa
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <[email protected]>
>
> All warnings (new ones prefixed by >>, old ones prefixed by <<):
>
> In file included from include/linux/kernel.h:11,
> from include/linux/list.h:9,
> from include/linux/preempt.h:11,
> from include/linux/spinlock.h:51,
> from drivers/target/target_core_user.c:9:
> include/linux/scatterlist.h: In function 'sg_set_buf':
> arch/xtensa/include/asm/page.h:193:9: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
> 193 | ((pfn) >= ARCH_PFN_OFFSET && ((pfn) - ARCH_PFN_OFFSET) < max_mapnr)
> | ^~
> include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
> 78 | # define unlikely(x) __builtin_expect(!!(x), 0)
> | ^
> include/linux/scatterlist.h:143:2: note: in expansion of macro 'BUG_ON'
> 143 | BUG_ON(!virt_addr_valid(buf));
> | ^~~~~~
> arch/xtensa/include/asm/page.h:201:32: note: in expansion of macro 'pfn_valid'
> 201 | #define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
> | ^~~~~~~~~
> include/linux/scatterlist.h:143:10: note: in expansion of macro 'virt_addr_valid'
> 143 | BUG_ON(!virt_addr_valid(buf));
> | ^~~~~~~~~~~~~~~
> In file included from ./arch/xtensa/include/generated/asm/bug.h:1,
> from include/linux/bug.h:5,
> from include/linux/thread_info.h:12,
> from include/asm-generic/preempt.h:5,
> from ./arch/xtensa/include/generated/asm/preempt.h:1,
> from include/linux/preempt.h:78,
> from include/linux/spinlock.h:51,
> from drivers/target/target_core_user.c:9:
> include/linux/dma-mapping.h: In function 'dma_map_resource':
> arch/xtensa/include/asm/page.h:193:9: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
> 193 | ((pfn) >= ARCH_PFN_OFFSET && ((pfn) - ARCH_PFN_OFFSET) < max_mapnr)
> | ^~
> include/asm-generic/bug.h:144:27: note: in definition of macro 'WARN_ON_ONCE'
> 144 | int __ret_warn_once = !!(condition); | ^~~~~~~~~
> include/linux/dma-mapping.h:352:19: note: in expansion of macro 'pfn_valid'
> 352 | if (WARN_ON_ONCE(pfn_valid(PHYS_PFN(phys_addr))))
> | ^~~~~~~~~
> In file included from include/linux/mm_types_task.h:16,
> from include/linux/mm_types.h:5,
> from include/linux/mmzone.h:21,
> from include/linux/gfp.h:6,
> from include/linux/umh.h:4,
> from include/linux/kmod.h:9,
> from include/linux/module.h:16,
> from drivers/target/target_core_user.c:10:
> drivers/target/target_core_user.c: In function 'tcmu_flush_dcache_range':
> arch/xtensa/include/asm/page.h:193:9: warning: comparison of unsigned expression >= 0 is always true [-Wtype-limits]
> 193 | ((pfn) >= ARCH_PFN_OFFSET && ((pfn) - ARCH_PFN_OFFSET) < max_mapnr)
> | ^~
> arch/xtensa/include/asm/page.h:201:32: note: in expansion of macro 'pfn_valid'
> 201 | #define virt_addr_valid(kaddr) pfn_valid(__pa(kaddr) >> PAGE_SHIFT)
> | ^~~~~~~~~
> drivers/target/target_core_user.c:605:7: note: in expansion of macro 'virt_addr_valid'
> 605 | if (virt_addr_valid(start))
> | ^~~~~~~~~~~~~~~
>>> drivers/target/target_core_user.c:600:15: warning: variable 'pg' set but not used [-Wunused-but-set-variable]
> 600 | struct page *pg;
> | ^~
>
> vim +/pg +600 drivers/target/target_core_user.c
>
> 595
> 596 static inline void tcmu_flush_dcache_range(void *vaddr, size_t size)
> 597 {
> 598 unsigned long offset = offset_in_page(vaddr);
> 599 void *start = vaddr - offset;
> > 600 struct page *pg;
> 601
> 602 size = round_up(size+offset, PAGE_SIZE);
> 603
> 604 while (size) {
> 605 if (virt_addr_valid(start))
> 606 pg = virt_to_page(start);
> 607 else if (is_vmalloc_addr(start))
> 608 pg = vmalloc_to_page(start);
> 609 else
> 610 break;
> 611
> 612 flush_dcache_page(pg);
> 613 start += PAGE_SIZE;
> 614 size -= PAGE_SIZE;
> 615 }
> 616 }
> 617
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/[email protected]
It doesn't really matter in this case because this patch has been
superseded by a different fix, but the warning appears to be caused by
an incorrect implementation of flush_dcache_page() in
arch/xtensa/include/asm/cacheflush.h. Depending on the variant and
options, flush_dcache_page can be defined as "do { } while (0)", which
covers the default null implementation of flush_dcache_page().
Thanks,
Henry