* [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates
@ 2020-10-22 6:07 Aneesh Kumar K.V
2020-10-22 8:34 ` Sachin Sant
` (2 more replies)
0 siblings, 3 replies; 12+ messages in thread
From: Aneesh Kumar K.V @ 2020-10-22 6:07 UTC (permalink / raw)
To: linux-mm
Cc: akpm, Aneesh Kumar K.V, Christoph Hellwig, Sachin Sant,
linux-nvdimm, Jason Gunthorpe
commit 6f42193fd86e ("memremap: don't use a separate devm action for
devmap_managed_enable_get") changed the static key updates such that we
now call devmap_managed_enable_put() without doing the equivalent
devmap_managed_enable_get().
devmap_managed_enable_get() is only called for MEMORY_DEVICE_PRIVATE and
MEMORY_DEVICE_FS_DAX, But memunmap_pages() get called for other pgmap
types too. This results in the below warning when switching between
system-ram and devdax mode for devdax namespace.
jump label: negative count!
WARNING: CPU: 52 PID: 1335 at kernel/jump_label.c:235 static_key_slow_try_dec+0x88/0xa0
Modules linked in:
....
NIP [c000000000433318] static_key_slow_try_dec+0x88/0xa0
LR [c000000000433314] static_key_slow_try_dec+0x84/0xa0
Call Trace:
[c000000025c1f660] [c000000000433314] static_key_slow_try_dec+0x84/0xa0 (unreliable)
[c000000025c1f6d0] [c000000000433664] __static_key_slow_dec_cpuslocked+0x34/0xd0
[c000000025c1f700] [c0000000004337a4] static_key_slow_dec+0x54/0xf0
[c000000025c1f770] [c00000000059c49c] memunmap_pages+0x36c/0x500
[c000000025c1f820] [c000000000d91d10] devm_action_release+0x30/0x50
[c000000025c1f840] [c000000000d92e34] release_nodes+0x2f4/0x3e0
[c000000025c1f8f0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
[c000000025c1f930] [c000000000d883a4] bus_remove_device+0x124/0x210
[c000000025c1f9b0] [c000000000d80ef4] device_del+0x1d4/0x530
[c000000025c1fa70] [c000000000e341e8] unregister_dev_dax+0x48/0xe0
[c000000025c1fae0] [c000000000d91d10] devm_action_release+0x30/0x50
[c000000025c1fb00] [c000000000d92e34] release_nodes+0x2f4/0x3e0
[c000000025c1fbb0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
[c000000025c1fbf0] [c000000000d87000] unbind_store+0x130/0x170
[c000000025c1fc30] [c000000000d862a0] drv_attr_store+0x40/0x60
[c000000025c1fc50] [c0000000006d316c] sysfs_kf_write+0x6c/0xb0
[c000000025c1fc90] [c0000000006d2328] kernfs_fop_write+0x118/0x280
[c000000025c1fce0] [c0000000005a79f8] vfs_write+0xe8/0x2a0
[c000000025c1fd30] [c0000000005a7d94] ksys_write+0x84/0x140
[c000000025c1fd80] [c00000000003a430] system_call_exception+0x120/0x270
[c000000025c1fe20] [c00000000000c540] system_call_common+0xf0/0x27c
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Sachin Sant <sachinp@linux.vnet.ibm.com>
Cc: linux-nvdimm@lists.01.org
Cc: Ira Weiny <ira.weiny@intel.com>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
---
mm/memremap.c | 19 +++++++++++++++----
1 file changed, 15 insertions(+), 4 deletions(-)
diff --git a/mm/memremap.c b/mm/memremap.c
index 73a206d0f645..d4402ff3e467 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -158,6 +158,16 @@ void memunmap_pages(struct dev_pagemap *pgmap)
{
unsigned long pfn;
int i;
+ bool need_devmap_managed = false;
+
+ switch (pgmap->type) {
+ case MEMORY_DEVICE_PRIVATE:
+ case MEMORY_DEVICE_FS_DAX:
+ need_devmap_managed = true;
+ break;
+ default:
+ break;
+ }
dev_pagemap_kill(pgmap);
for (i = 0; i < pgmap->nr_range; i++)
@@ -169,7 +179,8 @@ void memunmap_pages(struct dev_pagemap *pgmap)
pageunmap_range(pgmap, i);
WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
- devmap_managed_enable_put();
+ if (need_devmap_managed)
+ devmap_managed_enable_put();
}
EXPORT_SYMBOL_GPL(memunmap_pages);
@@ -307,7 +318,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
.pgprot = PAGE_KERNEL,
};
const int nr_range = pgmap->nr_range;
- bool need_devmap_managed = true;
+ bool need_devmap_managed = false;
int error, i;
if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
@@ -327,6 +338,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
WARN(1, "Missing owner\n");
return ERR_PTR(-EINVAL);
}
+ need_devmap_managed = true;
break;
case MEMORY_DEVICE_FS_DAX:
if (!IS_ENABLED(CONFIG_ZONE_DEVICE) ||
@@ -334,13 +346,12 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
WARN(1, "File system DAX not supported\n");
return ERR_PTR(-EINVAL);
}
+ need_devmap_managed = true;
break;
case MEMORY_DEVICE_GENERIC:
- need_devmap_managed = false;
break;
case MEMORY_DEVICE_PCI_P2PDMA:
params.pgprot = pgprot_noncached(params.pgprot);
- need_devmap_managed = false;
break;
default:
WARN(1, "Invalid pgmap type %d\n", pgmap->type);
--
2.26.2
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^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates
2020-10-22 6:07 [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates Aneesh Kumar K.V
@ 2020-10-22 8:34 ` Sachin Sant
2020-10-22 13:26 ` Christoph Hellwig
2020-10-22 15:41 ` Ira Weiny
2 siblings, 0 replies; 12+ messages in thread
From: Sachin Sant @ 2020-10-22 8:34 UTC (permalink / raw)
To: Aneesh Kumar K.V
Cc: linux-mm, akpm, Christoph Hellwig, linux-nvdimm, Jason Gunthorpe
> jump label: negative count!
> WARNING: CPU: 52 PID: 1335 at kernel/jump_label.c:235 static_key_slow_try_dec+0x88/0xa0
> Modules linked in:
> ….
>
> Cc: Christoph Hellwig <hch@infradead.org>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Sachin Sant <sachinp@linux.vnet.ibm.com>
> Cc: linux-nvdimm@lists.01.org
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: Jason Gunthorpe <jgg@mellanox.com>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> —
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
-Sachin
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates
2020-10-22 6:07 [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates Aneesh Kumar K.V
2020-10-22 8:34 ` Sachin Sant
@ 2020-10-22 13:26 ` Christoph Hellwig
2020-10-22 15:41 ` Ira Weiny
2 siblings, 0 replies; 12+ messages in thread
From: Christoph Hellwig @ 2020-10-22 13:26 UTC (permalink / raw)
To: Aneesh Kumar K.V
Cc: linux-mm, akpm, Christoph Hellwig, Sachin Sant, linux-nvdimm,
Jason Gunthorpe
Looks good,
Reviewed-by: Christoph Hellwig <hch@lst.de>
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates
2020-10-22 6:07 [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates Aneesh Kumar K.V
2020-10-22 8:34 ` Sachin Sant
2020-10-22 13:26 ` Christoph Hellwig
@ 2020-10-22 15:41 ` Ira Weiny
2020-10-22 18:19 ` Ralph Campbell
2 siblings, 1 reply; 12+ messages in thread
From: Ira Weiny @ 2020-10-22 15:41 UTC (permalink / raw)
To: Aneesh Kumar K.V
Cc: linux-mm, akpm, Christoph Hellwig, Sachin Sant, linux-nvdimm,
Jason Gunthorpe, Ralph Campbell
On Thu, Oct 22, 2020 at 11:37:53AM +0530, Aneesh Kumar K.V wrote:
> commit 6f42193fd86e ("memremap: don't use a separate devm action for
> devmap_managed_enable_get") changed the static key updates such that we
> now call devmap_managed_enable_put() without doing the equivalent
> devmap_managed_enable_get().
>
> devmap_managed_enable_get() is only called for MEMORY_DEVICE_PRIVATE and
> MEMORY_DEVICE_FS_DAX, But memunmap_pages() get called for other pgmap
> types too. This results in the below warning when switching between
> system-ram and devdax mode for devdax namespace.
>
> jump label: negative count!
> WARNING: CPU: 52 PID: 1335 at kernel/jump_label.c:235 static_key_slow_try_dec+0x88/0xa0
> Modules linked in:
> ....
>
> NIP [c000000000433318] static_key_slow_try_dec+0x88/0xa0
> LR [c000000000433314] static_key_slow_try_dec+0x84/0xa0
> Call Trace:
> [c000000025c1f660] [c000000000433314] static_key_slow_try_dec+0x84/0xa0 (unreliable)
> [c000000025c1f6d0] [c000000000433664] __static_key_slow_dec_cpuslocked+0x34/0xd0
> [c000000025c1f700] [c0000000004337a4] static_key_slow_dec+0x54/0xf0
> [c000000025c1f770] [c00000000059c49c] memunmap_pages+0x36c/0x500
> [c000000025c1f820] [c000000000d91d10] devm_action_release+0x30/0x50
> [c000000025c1f840] [c000000000d92e34] release_nodes+0x2f4/0x3e0
> [c000000025c1f8f0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
> [c000000025c1f930] [c000000000d883a4] bus_remove_device+0x124/0x210
> [c000000025c1f9b0] [c000000000d80ef4] device_del+0x1d4/0x530
> [c000000025c1fa70] [c000000000e341e8] unregister_dev_dax+0x48/0xe0
> [c000000025c1fae0] [c000000000d91d10] devm_action_release+0x30/0x50
> [c000000025c1fb00] [c000000000d92e34] release_nodes+0x2f4/0x3e0
> [c000000025c1fbb0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
> [c000000025c1fbf0] [c000000000d87000] unbind_store+0x130/0x170
> [c000000025c1fc30] [c000000000d862a0] drv_attr_store+0x40/0x60
> [c000000025c1fc50] [c0000000006d316c] sysfs_kf_write+0x6c/0xb0
> [c000000025c1fc90] [c0000000006d2328] kernfs_fop_write+0x118/0x280
> [c000000025c1fce0] [c0000000005a79f8] vfs_write+0xe8/0x2a0
> [c000000025c1fd30] [c0000000005a7d94] ksys_write+0x84/0x140
> [c000000025c1fd80] [c00000000003a430] system_call_exception+0x120/0x270
> [c000000025c1fe20] [c00000000000c540] system_call_common+0xf0/0x27c
>
> Cc: Christoph Hellwig <hch@infradead.org>
> Cc: Dan Williams <dan.j.williams@intel.com>
> Cc: Sachin Sant <sachinp@linux.vnet.ibm.com>
> Cc: linux-nvdimm@lists.01.org
> Cc: Ira Weiny <ira.weiny@intel.com>
> Cc: Jason Gunthorpe <jgg@mellanox.com>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> ---
> mm/memremap.c | 19 +++++++++++++++----
> 1 file changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/mm/memremap.c b/mm/memremap.c
> index 73a206d0f645..d4402ff3e467 100644
> --- a/mm/memremap.c
> +++ b/mm/memremap.c
> @@ -158,6 +158,16 @@ void memunmap_pages(struct dev_pagemap *pgmap)
> {
> unsigned long pfn;
> int i;
> + bool need_devmap_managed = false;
> +
> + switch (pgmap->type) {
> + case MEMORY_DEVICE_PRIVATE:
> + case MEMORY_DEVICE_FS_DAX:
> + need_devmap_managed = true;
> + break;
> + default:
> + break;
> + }
Is it overkill to avoid duplicating this switch logic in
page_is_devmap_managed() by creating another call which can be used here?
>
> dev_pagemap_kill(pgmap);
> for (i = 0; i < pgmap->nr_range; i++)
> @@ -169,7 +179,8 @@ void memunmap_pages(struct dev_pagemap *pgmap)
> pageunmap_range(pgmap, i);
>
> WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
> - devmap_managed_enable_put();
> + if (need_devmap_managed)
> + devmap_managed_enable_put();
> }
> EXPORT_SYMBOL_GPL(memunmap_pages);
>
> @@ -307,7 +318,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
> .pgprot = PAGE_KERNEL,
> };
> const int nr_range = pgmap->nr_range;
> - bool need_devmap_managed = true;
> + bool need_devmap_managed = false;
I'm CC'ing Ralph Campbell because I think some of his work has proposed this
same change.
Ira
> int error, i;
>
> if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
> @@ -327,6 +338,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
> WARN(1, "Missing owner\n");
> return ERR_PTR(-EINVAL);
> }
> + need_devmap_managed = true;
> break;
> case MEMORY_DEVICE_FS_DAX:
> if (!IS_ENABLED(CONFIG_ZONE_DEVICE) ||
> @@ -334,13 +346,12 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
> WARN(1, "File system DAX not supported\n");
> return ERR_PTR(-EINVAL);
> }
> + need_devmap_managed = true;
> break;
> case MEMORY_DEVICE_GENERIC:
> - need_devmap_managed = false;
> break;
> case MEMORY_DEVICE_PCI_P2PDMA:
> params.pgprot = pgprot_noncached(params.pgprot);
> - need_devmap_managed = false;
> break;
> default:
> WARN(1, "Invalid pgmap type %d\n", pgmap->type);
> --
> 2.26.2
>
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates
2020-10-22 15:41 ` Ira Weiny
@ 2020-10-22 18:19 ` Ralph Campbell
2020-10-22 19:10 ` Ira Weiny
` (2 more replies)
0 siblings, 3 replies; 12+ messages in thread
From: Ralph Campbell @ 2020-10-22 18:19 UTC (permalink / raw)
To: Ira Weiny, Aneesh Kumar K.V
Cc: linux-mm, akpm, Christoph Hellwig, Sachin Sant, linux-nvdimm,
Jason Gunthorpe
On 10/22/20 8:41 AM, Ira Weiny wrote:
> On Thu, Oct 22, 2020 at 11:37:53AM +0530, Aneesh Kumar K.V wrote:
>> commit 6f42193fd86e ("memremap: don't use a separate devm action for
>> devmap_managed_enable_get") changed the static key updates such that we
>> now call devmap_managed_enable_put() without doing the equivalent
>> devmap_managed_enable_get().
>>
>> devmap_managed_enable_get() is only called for MEMORY_DEVICE_PRIVATE and
>> MEMORY_DEVICE_FS_DAX, But memunmap_pages() get called for other pgmap
>> types too. This results in the below warning when switching between
>> system-ram and devdax mode for devdax namespace.
>>
>> jump label: negative count!
>> WARNING: CPU: 52 PID: 1335 at kernel/jump_label.c:235 static_key_slow_try_dec+0x88/0xa0
>> Modules linked in:
>> ....
>>
>> NIP [c000000000433318] static_key_slow_try_dec+0x88/0xa0
>> LR [c000000000433314] static_key_slow_try_dec+0x84/0xa0
>> Call Trace:
>> [c000000025c1f660] [c000000000433314] static_key_slow_try_dec+0x84/0xa0 (unreliable)
>> [c000000025c1f6d0] [c000000000433664] __static_key_slow_dec_cpuslocked+0x34/0xd0
>> [c000000025c1f700] [c0000000004337a4] static_key_slow_dec+0x54/0xf0
>> [c000000025c1f770] [c00000000059c49c] memunmap_pages+0x36c/0x500
>> [c000000025c1f820] [c000000000d91d10] devm_action_release+0x30/0x50
>> [c000000025c1f840] [c000000000d92e34] release_nodes+0x2f4/0x3e0
>> [c000000025c1f8f0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
>> [c000000025c1f930] [c000000000d883a4] bus_remove_device+0x124/0x210
>> [c000000025c1f9b0] [c000000000d80ef4] device_del+0x1d4/0x530
>> [c000000025c1fa70] [c000000000e341e8] unregister_dev_dax+0x48/0xe0
>> [c000000025c1fae0] [c000000000d91d10] devm_action_release+0x30/0x50
>> [c000000025c1fb00] [c000000000d92e34] release_nodes+0x2f4/0x3e0
>> [c000000025c1fbb0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
>> [c000000025c1fbf0] [c000000000d87000] unbind_store+0x130/0x170
>> [c000000025c1fc30] [c000000000d862a0] drv_attr_store+0x40/0x60
>> [c000000025c1fc50] [c0000000006d316c] sysfs_kf_write+0x6c/0xb0
>> [c000000025c1fc90] [c0000000006d2328] kernfs_fop_write+0x118/0x280
>> [c000000025c1fce0] [c0000000005a79f8] vfs_write+0xe8/0x2a0
>> [c000000025c1fd30] [c0000000005a7d94] ksys_write+0x84/0x140
>> [c000000025c1fd80] [c00000000003a430] system_call_exception+0x120/0x270
>> [c000000025c1fe20] [c00000000000c540] system_call_common+0xf0/0x27c
>>
>> Cc: Christoph Hellwig <hch@infradead.org>
>> Cc: Dan Williams <dan.j.williams@intel.com>
>> Cc: Sachin Sant <sachinp@linux.vnet.ibm.com>
>> Cc: linux-nvdimm@lists.01.org
>> Cc: Ira Weiny <ira.weiny@intel.com>
>> Cc: Jason Gunthorpe <jgg@mellanox.com>
>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>> ---
>> mm/memremap.c | 19 +++++++++++++++----
>> 1 file changed, 15 insertions(+), 4 deletions(-)
>>
>> diff --git a/mm/memremap.c b/mm/memremap.c
>> index 73a206d0f645..d4402ff3e467 100644
>> --- a/mm/memremap.c
>> +++ b/mm/memremap.c
>> @@ -158,6 +158,16 @@ void memunmap_pages(struct dev_pagemap *pgmap)
>> {
>> unsigned long pfn;
>> int i;
>> + bool need_devmap_managed = false;
>> +
>> + switch (pgmap->type) {
>> + case MEMORY_DEVICE_PRIVATE:
>> + case MEMORY_DEVICE_FS_DAX:
>> + need_devmap_managed = true;
>> + break;
>> + default:
>> + break;
>> + }
>
> Is it overkill to avoid duplicating this switch logic in
> page_is_devmap_managed() by creating another call which can be used here?
Perhaps. I can imagine a helper defined in include/linux/mm.h which
page_is_devmap_managed() could also call but that would impact a lot of
places that include mm.h. Since memremap.c already has to have intimate
knowledge of the pgmap->type, I think limiting the change to just what
is needed is better for now. So the patch looks OK to me.
Looking at this some more, I would suggest changing devmap_managed_enable_get()
and devmap_managed_enable_put() to do the special case checking instead of
doing it in memremap_pages() and memunmap_pages().
Then devmap_managed_enable_get() doesn't need to return an error if
CONFIG_DEV_PAGEMAP_OPS isn't defined. I have only compile tested the
following.
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
---
mm/memremap.c | 39 ++++++++++++++++-----------------------
1 file changed, 16 insertions(+), 23 deletions(-)
diff --git a/mm/memremap.c b/mm/memremap.c
index 73a206d0f645..16b2fb482da1 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -41,28 +41,24 @@ EXPORT_SYMBOL_GPL(memremap_compat_align);
DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
EXPORT_SYMBOL(devmap_managed_key);
-static void devmap_managed_enable_put(void)
+static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
{
- static_branch_dec(&devmap_managed_key);
+ if (pgmap->type == MEMORY_DEVICE_PRIVATE ||
+ pgmap->type == MEMORY_DEVICE_FS_DAX)
+ static_branch_dec(&devmap_managed_key);
}
-static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
+static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
{
- if (pgmap->type == MEMORY_DEVICE_PRIVATE &&
- (!pgmap->ops || !pgmap->ops->page_free)) {
- WARN(1, "Missing page_free method\n");
- return -EINVAL;
- }
-
- static_branch_inc(&devmap_managed_key);
- return 0;
+ if (pgmap->type == MEMORY_DEVICE_PRIVATE ||
+ pgmap->type == MEMORY_DEVICE_FS_DAX)
+ static_branch_inc(&devmap_managed_key);
}
#else
-static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
+static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
{
- return -EINVAL;
}
-static void devmap_managed_enable_put(void)
+static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
{
}
#endif /* CONFIG_DEV_PAGEMAP_OPS */
@@ -169,7 +165,7 @@ void memunmap_pages(struct dev_pagemap *pgmap)
pageunmap_range(pgmap, i);
WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
- devmap_managed_enable_put();
+ devmap_managed_enable_put(pgmap);
}
EXPORT_SYMBOL_GPL(memunmap_pages);
@@ -307,7 +303,6 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
.pgprot = PAGE_KERNEL,
};
const int nr_range = pgmap->nr_range;
- bool need_devmap_managed = true;
int error, i;
if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
@@ -323,6 +318,10 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
WARN(1, "Missing migrate_to_ram method\n");
return ERR_PTR(-EINVAL);
}
+ if (!pgmap->ops->page_free) {
+ WARN(1, "Missing page_free method\n");
+ return ERR_PTR(-EINVAL);
+ }
if (!pgmap->owner) {
WARN(1, "Missing owner\n");
return ERR_PTR(-EINVAL);
@@ -336,11 +335,9 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
}
break;
case MEMORY_DEVICE_GENERIC:
- need_devmap_managed = false;
break;
case MEMORY_DEVICE_PCI_P2PDMA:
params.pgprot = pgprot_noncached(params.pgprot);
- need_devmap_managed = false;
break;
default:
WARN(1, "Invalid pgmap type %d\n", pgmap->type);
@@ -364,11 +361,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
}
}
- if (need_devmap_managed) {
- error = devmap_managed_enable_get(pgmap);
- if (error)
- return ERR_PTR(error);
- }
+ devmap_managed_enable_get(pgmap);
/*
* Clear the pgmap nr_range as it will be incremented for each
--
2.20.1
>>
>> dev_pagemap_kill(pgmap);
>> for (i = 0; i < pgmap->nr_range; i++)
>> @@ -169,7 +179,8 @@ void memunmap_pages(struct dev_pagemap *pgmap)
>> pageunmap_range(pgmap, i);
>>
>> WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
>> - devmap_managed_enable_put();
>> + if (need_devmap_managed)
>> + devmap_managed_enable_put();
>> }
>> EXPORT_SYMBOL_GPL(memunmap_pages);
>>
>> @@ -307,7 +318,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
>> .pgprot = PAGE_KERNEL,
>> };
>> const int nr_range = pgmap->nr_range;
>> - bool need_devmap_managed = true;
>> + bool need_devmap_managed = false;
>
> I'm CC'ing Ralph Campbell because I think some of his work has proposed this
> same change.
>
> Ira
This part of the patch isn't strictly needed, it just reverses the default value of
need_devmap_managed.
>> int error, i;
>>
>> if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
>> @@ -327,6 +338,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
>> WARN(1, "Missing owner\n");
>> return ERR_PTR(-EINVAL);
>> }
>> + need_devmap_managed = true;
>> break;
>> case MEMORY_DEVICE_FS_DAX:
>> if (!IS_ENABLED(CONFIG_ZONE_DEVICE) ||
>> @@ -334,13 +346,12 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
>> WARN(1, "File system DAX not supported\n");
>> return ERR_PTR(-EINVAL);
>> }
>> + need_devmap_managed = true;
>> break;
>> case MEMORY_DEVICE_GENERIC:
>> - need_devmap_managed = false;
>> break;
>> case MEMORY_DEVICE_PCI_P2PDMA:
>> params.pgprot = pgprot_noncached(params.pgprot);
>> - need_devmap_managed = false;
>> break;
>> default:
>> WARN(1, "Invalid pgmap type %d\n", pgmap->type);
>> --
>> 2.26.2
>>
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* Re: [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates
2020-10-22 18:19 ` Ralph Campbell
@ 2020-10-22 19:10 ` Ira Weiny
2020-10-23 2:52 ` Aneesh Kumar K.V
2020-10-23 6:38 ` Sachin Sant
2020-10-23 6:46 ` Christoph Hellwig
2 siblings, 1 reply; 12+ messages in thread
From: Ira Weiny @ 2020-10-22 19:10 UTC (permalink / raw)
To: Ralph Campbell
Cc: Aneesh Kumar K.V, linux-mm, akpm, Christoph Hellwig, Sachin Sant,
linux-nvdimm, Jason Gunthorpe
On Thu, Oct 22, 2020 at 11:19:43AM -0700, Ralph Campbell wrote:
>
> On 10/22/20 8:41 AM, Ira Weiny wrote:
> > On Thu, Oct 22, 2020 at 11:37:53AM +0530, Aneesh Kumar K.V wrote:
> > > commit 6f42193fd86e ("memremap: don't use a separate devm action for
> > > devmap_managed_enable_get") changed the static key updates such that we
> > > now call devmap_managed_enable_put() without doing the equivalent
> > > devmap_managed_enable_get().
> > >
> > > devmap_managed_enable_get() is only called for MEMORY_DEVICE_PRIVATE and
> > > MEMORY_DEVICE_FS_DAX, But memunmap_pages() get called for other pgmap
> > > types too. This results in the below warning when switching between
> > > system-ram and devdax mode for devdax namespace.
> > >
> > > jump label: negative count!
> > > WARNING: CPU: 52 PID: 1335 at kernel/jump_label.c:235 static_key_slow_try_dec+0x88/0xa0
> > > Modules linked in:
> > > ....
> > >
> > > NIP [c000000000433318] static_key_slow_try_dec+0x88/0xa0
> > > LR [c000000000433314] static_key_slow_try_dec+0x84/0xa0
> > > Call Trace:
> > > [c000000025c1f660] [c000000000433314] static_key_slow_try_dec+0x84/0xa0 (unreliable)
> > > [c000000025c1f6d0] [c000000000433664] __static_key_slow_dec_cpuslocked+0x34/0xd0
> > > [c000000025c1f700] [c0000000004337a4] static_key_slow_dec+0x54/0xf0
> > > [c000000025c1f770] [c00000000059c49c] memunmap_pages+0x36c/0x500
> > > [c000000025c1f820] [c000000000d91d10] devm_action_release+0x30/0x50
> > > [c000000025c1f840] [c000000000d92e34] release_nodes+0x2f4/0x3e0
> > > [c000000025c1f8f0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
> > > [c000000025c1f930] [c000000000d883a4] bus_remove_device+0x124/0x210
> > > [c000000025c1f9b0] [c000000000d80ef4] device_del+0x1d4/0x530
> > > [c000000025c1fa70] [c000000000e341e8] unregister_dev_dax+0x48/0xe0
> > > [c000000025c1fae0] [c000000000d91d10] devm_action_release+0x30/0x50
> > > [c000000025c1fb00] [c000000000d92e34] release_nodes+0x2f4/0x3e0
> > > [c000000025c1fbb0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
> > > [c000000025c1fbf0] [c000000000d87000] unbind_store+0x130/0x170
> > > [c000000025c1fc30] [c000000000d862a0] drv_attr_store+0x40/0x60
> > > [c000000025c1fc50] [c0000000006d316c] sysfs_kf_write+0x6c/0xb0
> > > [c000000025c1fc90] [c0000000006d2328] kernfs_fop_write+0x118/0x280
> > > [c000000025c1fce0] [c0000000005a79f8] vfs_write+0xe8/0x2a0
> > > [c000000025c1fd30] [c0000000005a7d94] ksys_write+0x84/0x140
> > > [c000000025c1fd80] [c00000000003a430] system_call_exception+0x120/0x270
> > > [c000000025c1fe20] [c00000000000c540] system_call_common+0xf0/0x27c
> > >
> > > Cc: Christoph Hellwig <hch@infradead.org>
> > > Cc: Dan Williams <dan.j.williams@intel.com>
> > > Cc: Sachin Sant <sachinp@linux.vnet.ibm.com>
> > > Cc: linux-nvdimm@lists.01.org
> > > Cc: Ira Weiny <ira.weiny@intel.com>
> > > Cc: Jason Gunthorpe <jgg@mellanox.com>
> > > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> > > ---
> > > mm/memremap.c | 19 +++++++++++++++----
> > > 1 file changed, 15 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/mm/memremap.c b/mm/memremap.c
> > > index 73a206d0f645..d4402ff3e467 100644
> > > --- a/mm/memremap.c
> > > +++ b/mm/memremap.c
> > > @@ -158,6 +158,16 @@ void memunmap_pages(struct dev_pagemap *pgmap)
> > > {
> > > unsigned long pfn;
> > > int i;
> > > + bool need_devmap_managed = false;
> > > +
> > > + switch (pgmap->type) {
> > > + case MEMORY_DEVICE_PRIVATE:
> > > + case MEMORY_DEVICE_FS_DAX:
> > > + need_devmap_managed = true;
> > > + break;
> > > + default:
> > > + break;
> > > + }
> >
> > Is it overkill to avoid duplicating this switch logic in
> > page_is_devmap_managed() by creating another call which can be used here?
>
> Perhaps. I can imagine a helper defined in include/linux/mm.h which
> page_is_devmap_managed() could also call but that would impact a lot of
> places that include mm.h. Since memremap.c already has to have intimate
> knowledge of the pgmap->type, I think limiting the change to just what
> is needed is better for now. So the patch looks OK to me.
>
> Looking at this some more, I would suggest changing devmap_managed_enable_get()
> and devmap_managed_enable_put() to do the special case checking instead of
> doing it in memremap_pages() and memunmap_pages().
> Then devmap_managed_enable_get() doesn't need to return an error if
> CONFIG_DEV_PAGEMAP_OPS isn't defined. I have only compile tested the
> following.
This looks cleaner to me. Aneesh?
FWIW:
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Ira
>
> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
> ---
> mm/memremap.c | 39 ++++++++++++++++-----------------------
> 1 file changed, 16 insertions(+), 23 deletions(-)
>
> diff --git a/mm/memremap.c b/mm/memremap.c
> index 73a206d0f645..16b2fb482da1 100644
> --- a/mm/memremap.c
> +++ b/mm/memremap.c
> @@ -41,28 +41,24 @@ EXPORT_SYMBOL_GPL(memremap_compat_align);
> DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
> EXPORT_SYMBOL(devmap_managed_key);
> -static void devmap_managed_enable_put(void)
> +static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
> {
> - static_branch_dec(&devmap_managed_key);
> + if (pgmap->type == MEMORY_DEVICE_PRIVATE ||
> + pgmap->type == MEMORY_DEVICE_FS_DAX)
> + static_branch_dec(&devmap_managed_key);
> }
> -static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
> +static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
> {
> - if (pgmap->type == MEMORY_DEVICE_PRIVATE &&
> - (!pgmap->ops || !pgmap->ops->page_free)) {
> - WARN(1, "Missing page_free method\n");
> - return -EINVAL;
> - }
> -
> - static_branch_inc(&devmap_managed_key);
> - return 0;
> + if (pgmap->type == MEMORY_DEVICE_PRIVATE ||
> + pgmap->type == MEMORY_DEVICE_FS_DAX)
> + static_branch_inc(&devmap_managed_key);
> }
> #else
> -static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
> +static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
> {
> - return -EINVAL;
> }
> -static void devmap_managed_enable_put(void)
> +static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
> {
> }
> #endif /* CONFIG_DEV_PAGEMAP_OPS */
> @@ -169,7 +165,7 @@ void memunmap_pages(struct dev_pagemap *pgmap)
> pageunmap_range(pgmap, i);
> WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
> - devmap_managed_enable_put();
> + devmap_managed_enable_put(pgmap);
> }
> EXPORT_SYMBOL_GPL(memunmap_pages);
> @@ -307,7 +303,6 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
> .pgprot = PAGE_KERNEL,
> };
> const int nr_range = pgmap->nr_range;
> - bool need_devmap_managed = true;
> int error, i;
> if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
> @@ -323,6 +318,10 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
> WARN(1, "Missing migrate_to_ram method\n");
> return ERR_PTR(-EINVAL);
> }
> + if (!pgmap->ops->page_free) {
> + WARN(1, "Missing page_free method\n");
> + return ERR_PTR(-EINVAL);
> + }
> if (!pgmap->owner) {
> WARN(1, "Missing owner\n");
> return ERR_PTR(-EINVAL);
> @@ -336,11 +335,9 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
> }
> break;
> case MEMORY_DEVICE_GENERIC:
> - need_devmap_managed = false;
> break;
> case MEMORY_DEVICE_PCI_P2PDMA:
> params.pgprot = pgprot_noncached(params.pgprot);
> - need_devmap_managed = false;
> break;
> default:
> WARN(1, "Invalid pgmap type %d\n", pgmap->type);
> @@ -364,11 +361,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
> }
> }
> - if (need_devmap_managed) {
> - error = devmap_managed_enable_get(pgmap);
> - if (error)
> - return ERR_PTR(error);
> - }
> + devmap_managed_enable_get(pgmap);
> /*
> * Clear the pgmap nr_range as it will be incremented for each
> --
> 2.20.1
>
> > > dev_pagemap_kill(pgmap);
> > > for (i = 0; i < pgmap->nr_range; i++)
> > > @@ -169,7 +179,8 @@ void memunmap_pages(struct dev_pagemap *pgmap)
> > > pageunmap_range(pgmap, i);
> > > WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
> > > - devmap_managed_enable_put();
> > > + if (need_devmap_managed)
> > > + devmap_managed_enable_put();
> > > }
> > > EXPORT_SYMBOL_GPL(memunmap_pages);
> > > @@ -307,7 +318,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
> > > .pgprot = PAGE_KERNEL,
> > > };
> > > const int nr_range = pgmap->nr_range;
> > > - bool need_devmap_managed = true;
> > > + bool need_devmap_managed = false;
> >
> > I'm CC'ing Ralph Campbell because I think some of his work has proposed this
> > same change.
> >
> > Ira
>
> This part of the patch isn't strictly needed, it just reverses the default value of
> need_devmap_managed.
>
> > > int error, i;
> > > if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
> > > @@ -327,6 +338,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
> > > WARN(1, "Missing owner\n");
> > > return ERR_PTR(-EINVAL);
> > > }
> > > + need_devmap_managed = true;
> > > break;
> > > case MEMORY_DEVICE_FS_DAX:
> > > if (!IS_ENABLED(CONFIG_ZONE_DEVICE) ||
> > > @@ -334,13 +346,12 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
> > > WARN(1, "File system DAX not supported\n");
> > > return ERR_PTR(-EINVAL);
> > > }
> > > + need_devmap_managed = true;
> > > break;
> > > case MEMORY_DEVICE_GENERIC:
> > > - need_devmap_managed = false;
> > > break;
> > > case MEMORY_DEVICE_PCI_P2PDMA:
> > > params.pgprot = pgprot_noncached(params.pgprot);
> > > - need_devmap_managed = false;
> > > break;
> > > default:
> > > WARN(1, "Invalid pgmap type %d\n", pgmap->type);
> > > --
> > > 2.26.2
> > >
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates
2020-10-22 19:10 ` Ira Weiny
@ 2020-10-23 2:52 ` Aneesh Kumar K.V
0 siblings, 0 replies; 12+ messages in thread
From: Aneesh Kumar K.V @ 2020-10-23 2:52 UTC (permalink / raw)
To: Ira Weiny, Ralph Campbell
Cc: linux-mm, akpm, Christoph Hellwig, Sachin Sant, linux-nvdimm,
Jason Gunthorpe
On 10/23/20 12:40 AM, Ira Weiny wrote:
> On Thu, Oct 22, 2020 at 11:19:43AM -0700, Ralph Campbell wrote:
>>
>> On 10/22/20 8:41 AM, Ira Weiny wrote:
>>> On Thu, Oct 22, 2020 at 11:37:53AM +0530, Aneesh Kumar K.V wrote:
>>>> commit 6f42193fd86e ("memremap: don't use a separate devm action for
>>>> devmap_managed_enable_get") changed the static key updates such that we
>>>> now call devmap_managed_enable_put() without doing the equivalent
>>>> devmap_managed_enable_get().
>>>>
>>>> devmap_managed_enable_get() is only called for MEMORY_DEVICE_PRIVATE and
>>>> MEMORY_DEVICE_FS_DAX, But memunmap_pages() get called for other pgmap
>>>> types too. This results in the below warning when switching between
>>>> system-ram and devdax mode for devdax namespace.
>>>>
>>>> jump label: negative count!
>>>> WARNING: CPU: 52 PID: 1335 at kernel/jump_label.c:235 static_key_slow_try_dec+0x88/0xa0
>>>> Modules linked in:
>>>> ....
>>>>
>>>> NIP [c000000000433318] static_key_slow_try_dec+0x88/0xa0
>>>> LR [c000000000433314] static_key_slow_try_dec+0x84/0xa0
>>>> Call Trace:
>>>> [c000000025c1f660] [c000000000433314] static_key_slow_try_dec+0x84/0xa0 (unreliable)
>>>> [c000000025c1f6d0] [c000000000433664] __static_key_slow_dec_cpuslocked+0x34/0xd0
>>>> [c000000025c1f700] [c0000000004337a4] static_key_slow_dec+0x54/0xf0
>>>> [c000000025c1f770] [c00000000059c49c] memunmap_pages+0x36c/0x500
>>>> [c000000025c1f820] [c000000000d91d10] devm_action_release+0x30/0x50
>>>> [c000000025c1f840] [c000000000d92e34] release_nodes+0x2f4/0x3e0
>>>> [c000000025c1f8f0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
>>>> [c000000025c1f930] [c000000000d883a4] bus_remove_device+0x124/0x210
>>>> [c000000025c1f9b0] [c000000000d80ef4] device_del+0x1d4/0x530
>>>> [c000000025c1fa70] [c000000000e341e8] unregister_dev_dax+0x48/0xe0
>>>> [c000000025c1fae0] [c000000000d91d10] devm_action_release+0x30/0x50
>>>> [c000000025c1fb00] [c000000000d92e34] release_nodes+0x2f4/0x3e0
>>>> [c000000025c1fbb0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
>>>> [c000000025c1fbf0] [c000000000d87000] unbind_store+0x130/0x170
>>>> [c000000025c1fc30] [c000000000d862a0] drv_attr_store+0x40/0x60
>>>> [c000000025c1fc50] [c0000000006d316c] sysfs_kf_write+0x6c/0xb0
>>>> [c000000025c1fc90] [c0000000006d2328] kernfs_fop_write+0x118/0x280
>>>> [c000000025c1fce0] [c0000000005a79f8] vfs_write+0xe8/0x2a0
>>>> [c000000025c1fd30] [c0000000005a7d94] ksys_write+0x84/0x140
>>>> [c000000025c1fd80] [c00000000003a430] system_call_exception+0x120/0x270
>>>> [c000000025c1fe20] [c00000000000c540] system_call_common+0xf0/0x27c
>>>>
>>>> Cc: Christoph Hellwig <hch@infradead.org>
>>>> Cc: Dan Williams <dan.j.williams@intel.com>
>>>> Cc: Sachin Sant <sachinp@linux.vnet.ibm.com>
>>>> Cc: linux-nvdimm@lists.01.org
>>>> Cc: Ira Weiny <ira.weiny@intel.com>
>>>> Cc: Jason Gunthorpe <jgg@mellanox.com>
>>>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>>>> ---
>>>> mm/memremap.c | 19 +++++++++++++++----
>>>> 1 file changed, 15 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/mm/memremap.c b/mm/memremap.c
>>>> index 73a206d0f645..d4402ff3e467 100644
>>>> --- a/mm/memremap.c
>>>> +++ b/mm/memremap.c
>>>> @@ -158,6 +158,16 @@ void memunmap_pages(struct dev_pagemap *pgmap)
>>>> {
>>>> unsigned long pfn;
>>>> int i;
>>>> + bool need_devmap_managed = false;
>>>> +
>>>> + switch (pgmap->type) {
>>>> + case MEMORY_DEVICE_PRIVATE:
>>>> + case MEMORY_DEVICE_FS_DAX:
>>>> + need_devmap_managed = true;
>>>> + break;
>>>> + default:
>>>> + break;
>>>> + }
>>>
>>> Is it overkill to avoid duplicating this switch logic in
>>> page_is_devmap_managed() by creating another call which can be used here?
>>
>> Perhaps. I can imagine a helper defined in include/linux/mm.h which
>> page_is_devmap_managed() could also call but that would impact a lot of
>> places that include mm.h. Since memremap.c already has to have intimate
>> knowledge of the pgmap->type, I think limiting the change to just what
>> is needed is better for now. So the patch looks OK to me.
>>
>> Looking at this some more, I would suggest changing devmap_managed_enable_get()
>> and devmap_managed_enable_put() to do the special case checking instead of
>> doing it in memremap_pages() and memunmap_pages().
>> Then devmap_managed_enable_get() doesn't need to return an error if
>> CONFIG_DEV_PAGEMAP_OPS isn't defined. I have only compile tested the
>> following.
>
> This looks cleaner to me. Aneesh?
>
> FWIW:
> Reviewed-by: Ira Weiny <ira.weiny@intel.com>
>
>
Yes. You can add
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
-aneesh
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates
2020-10-22 18:19 ` Ralph Campbell
2020-10-22 19:10 ` Ira Weiny
@ 2020-10-23 6:38 ` Sachin Sant
2020-10-23 6:46 ` Christoph Hellwig
2 siblings, 0 replies; 12+ messages in thread
From: Sachin Sant @ 2020-10-23 6:38 UTC (permalink / raw)
To: Ralph Campbell
Cc: Aneesh Kumar K.V, linux-mm, akpm, Christoph Hellwig,
linux-nvdimm, Jason Gunthorpe
>> Is it overkill to avoid duplicating this switch logic in
>> page_is_devmap_managed() by creating another call which can be used here?
>
> Perhaps. I can imagine a helper defined in include/linux/mm.h which
> page_is_devmap_managed() could also call but that would impact a lot of
> places that include mm.h. Since memremap.c already has to have intimate
> knowledge of the pgmap->type, I think limiting the change to just what
> is needed is better for now. So the patch looks OK to me.
>
> Looking at this some more, I would suggest changing devmap_managed_enable_get()
> and devmap_managed_enable_put() to do the special case checking instead of
> doing it in memremap_pages() and memunmap_pages().
> Then devmap_managed_enable_get() doesn't need to return an error if
> CONFIG_DEV_PAGEMAP_OPS isn't defined. I have only compile tested the
> following.
>
> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
> —
This patch fixes the warning for me.
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
-Sachin
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates
2020-10-22 18:19 ` Ralph Campbell
2020-10-22 19:10 ` Ira Weiny
2020-10-23 6:38 ` Sachin Sant
@ 2020-10-23 6:46 ` Christoph Hellwig
2020-10-23 17:29 ` Ralph Campbell
2 siblings, 1 reply; 12+ messages in thread
From: Christoph Hellwig @ 2020-10-23 6:46 UTC (permalink / raw)
To: Ralph Campbell
Cc: Aneesh Kumar K.V, linux-mm, akpm, Christoph Hellwig, Sachin Sant,
linux-nvdimm, Jason Gunthorpe
On Thu, Oct 22, 2020 at 11:19:43AM -0700, Ralph Campbell wrote:
>
> On 10/22/20 8:41 AM, Ira Weiny wrote:
> > On Thu, Oct 22, 2020 at 11:37:53AM +0530, Aneesh Kumar K.V wrote:
> > > commit 6f42193fd86e ("memremap: don't use a separate devm action for
> > > devmap_managed_enable_get") changed the static key updates such that we
> > > now call devmap_managed_enable_put() without doing the equivalent
> > > devmap_managed_enable_get().
> > >
> > > devmap_managed_enable_get() is only called for MEMORY_DEVICE_PRIVATE and
> > > MEMORY_DEVICE_FS_DAX, But memunmap_pages() get called for other pgmap
> > > types too. This results in the below warning when switching between
> > > system-ram and devdax mode for devdax namespace.
> > >
> > > jump label: negative count!
> > > WARNING: CPU: 52 PID: 1335 at kernel/jump_label.c:235 static_key_slow_try_dec+0x88/0xa0
> > > Modules linked in:
> > > ....
> > >
> > > NIP [c000000000433318] static_key_slow_try_dec+0x88/0xa0
> > > LR [c000000000433314] static_key_slow_try_dec+0x84/0xa0
> > > Call Trace:
> > > [c000000025c1f660] [c000000000433314] static_key_slow_try_dec+0x84/0xa0 (unreliable)
> > > [c000000025c1f6d0] [c000000000433664] __static_key_slow_dec_cpuslocked+0x34/0xd0
> > > [c000000025c1f700] [c0000000004337a4] static_key_slow_dec+0x54/0xf0
> > > [c000000025c1f770] [c00000000059c49c] memunmap_pages+0x36c/0x500
> > > [c000000025c1f820] [c000000000d91d10] devm_action_release+0x30/0x50
> > > [c000000025c1f840] [c000000000d92e34] release_nodes+0x2f4/0x3e0
> > > [c000000025c1f8f0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
> > > [c000000025c1f930] [c000000000d883a4] bus_remove_device+0x124/0x210
> > > [c000000025c1f9b0] [c000000000d80ef4] device_del+0x1d4/0x530
> > > [c000000025c1fa70] [c000000000e341e8] unregister_dev_dax+0x48/0xe0
> > > [c000000025c1fae0] [c000000000d91d10] devm_action_release+0x30/0x50
> > > [c000000025c1fb00] [c000000000d92e34] release_nodes+0x2f4/0x3e0
> > > [c000000025c1fbb0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
> > > [c000000025c1fbf0] [c000000000d87000] unbind_store+0x130/0x170
> > > [c000000025c1fc30] [c000000000d862a0] drv_attr_store+0x40/0x60
> > > [c000000025c1fc50] [c0000000006d316c] sysfs_kf_write+0x6c/0xb0
> > > [c000000025c1fc90] [c0000000006d2328] kernfs_fop_write+0x118/0x280
> > > [c000000025c1fce0] [c0000000005a79f8] vfs_write+0xe8/0x2a0
> > > [c000000025c1fd30] [c0000000005a7d94] ksys_write+0x84/0x140
> > > [c000000025c1fd80] [c00000000003a430] system_call_exception+0x120/0x270
> > > [c000000025c1fe20] [c00000000000c540] system_call_common+0xf0/0x27c
> > >
> > > Cc: Christoph Hellwig <hch@infradead.org>
> > > Cc: Dan Williams <dan.j.williams@intel.com>
> > > Cc: Sachin Sant <sachinp@linux.vnet.ibm.com>
> > > Cc: linux-nvdimm@lists.01.org
> > > Cc: Ira Weiny <ira.weiny@intel.com>
> > > Cc: Jason Gunthorpe <jgg@mellanox.com>
> > > Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
> > > ---
> > > mm/memremap.c | 19 +++++++++++++++----
> > > 1 file changed, 15 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/mm/memremap.c b/mm/memremap.c
> > > index 73a206d0f645..d4402ff3e467 100644
> > > --- a/mm/memremap.c
> > > +++ b/mm/memremap.c
> > > @@ -158,6 +158,16 @@ void memunmap_pages(struct dev_pagemap *pgmap)
> > > {
> > > unsigned long pfn;
> > > int i;
> > > + bool need_devmap_managed = false;
> > > +
> > > + switch (pgmap->type) {
> > > + case MEMORY_DEVICE_PRIVATE:
> > > + case MEMORY_DEVICE_FS_DAX:
> > > + need_devmap_managed = true;
> > > + break;
> > > + default:
> > > + break;
> > > + }
> >
> > Is it overkill to avoid duplicating this switch logic in
> > page_is_devmap_managed() by creating another call which can be used here?
>
> Perhaps. I can imagine a helper defined in include/linux/mm.h which
> page_is_devmap_managed() could also call but that would impact a lot of
> places that include mm.h. Since memremap.c already has to have intimate
> knowledge of the pgmap->type, I think limiting the change to just what
> is needed is better for now. So the patch looks OK to me.
>
> Looking at this some more, I would suggest changing devmap_managed_enable_get()
> and devmap_managed_enable_put() to do the special case checking instead of
> doing it in memremap_pages() and memunmap_pages().
> Then devmap_managed_enable_get() doesn't need to return an error if
> CONFIG_DEV_PAGEMAP_OPS isn't defined. I have only compile tested the
> following.
>
> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
This looks ok as well. Can you submit it as a proper standalone patch?
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^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates
2020-10-23 6:46 ` Christoph Hellwig
@ 2020-10-23 17:29 ` Ralph Campbell
0 siblings, 0 replies; 12+ messages in thread
From: Ralph Campbell @ 2020-10-23 17:29 UTC (permalink / raw)
To: Christoph Hellwig; +Cc: Aneesh Kumar K.V, linux-mm, akpm, Sachin
On 10/22/20 11:46 PM, Christoph Hellwig wrote:
> On Thu, Oct 22, 2020 at 11:19:43AM -0700, Ralph Campbell wrote:
>>
>> On 10/22/20 8:41 AM, Ira Weiny wrote:
>>> On Thu, Oct 22, 2020 at 11:37:53AM +0530, Aneesh Kumar K.V wrote:
>>>> commit 6f42193fd86e ("memremap: don't use a separate devm action for
>>>> devmap_managed_enable_get") changed the static key updates such that we
>>>> now call devmap_managed_enable_put() without doing the equivalent
>>>> devmap_managed_enable_get().
>>>>
>>>> devmap_managed_enable_get() is only called for MEMORY_DEVICE_PRIVATE and
>>>> MEMORY_DEVICE_FS_DAX, But memunmap_pages() get called for other pgmap
>>>> types too. This results in the below warning when switching between
>>>> system-ram and devdax mode for devdax namespace.
>>>>
>>>> jump label: negative count!
>>>> WARNING: CPU: 52 PID: 1335 at kernel/jump_label.c:235 static_key_slow_try_dec+0x88/0xa0
>>>> Modules linked in:
>>>> ....
>>>>
>>>> NIP [c000000000433318] static_key_slow_try_dec+0x88/0xa0
>>>> LR [c000000000433314] static_key_slow_try_dec+0x84/0xa0
>>>> Call Trace:
>>>> [c000000025c1f660] [c000000000433314] static_key_slow_try_dec+0x84/0xa0 (unreliable)
>>>> [c000000025c1f6d0] [c000000000433664] __static_key_slow_dec_cpuslocked+0x34/0xd0
>>>> [c000000025c1f700] [c0000000004337a4] static_key_slow_dec+0x54/0xf0
>>>> [c000000025c1f770] [c00000000059c49c] memunmap_pages+0x36c/0x500
>>>> [c000000025c1f820] [c000000000d91d10] devm_action_release+0x30/0x50
>>>> [c000000025c1f840] [c000000000d92e34] release_nodes+0x2f4/0x3e0
>>>> [c000000025c1f8f0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
>>>> [c000000025c1f930] [c000000000d883a4] bus_remove_device+0x124/0x210
>>>> [c000000025c1f9b0] [c000000000d80ef4] device_del+0x1d4/0x530
>>>> [c000000025c1fa70] [c000000000e341e8] unregister_dev_dax+0x48/0xe0
>>>> [c000000025c1fae0] [c000000000d91d10] devm_action_release+0x30/0x50
>>>> [c000000025c1fb00] [c000000000d92e34] release_nodes+0x2f4/0x3e0
>>>> [c000000025c1fbb0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
>>>> [c000000025c1fbf0] [c000000000d87000] unbind_store+0x130/0x170
>>>> [c000000025c1fc30] [c000000000d862a0] drv_attr_store+0x40/0x60
>>>> [c000000025c1fc50] [c0000000006d316c] sysfs_kf_write+0x6c/0xb0
>>>> [c000000025c1fc90] [c0000000006d2328] kernfs_fop_write+0x118/0x280
>>>> [c000000025c1fce0] [c0000000005a79f8] vfs_write+0xe8/0x2a0
>>>> [c000000025c1fd30] [c0000000005a7d94] ksys_write+0x84/0x140
>>>> [c000000025c1fd80] [c00000000003a430] system_call_exception+0x120/0x270
>>>> [c000000025c1fe20] [c00000000000c540] system_call_common+0xf0/0x27c
>>>>
>>>> Cc: Christoph Hellwig <hch@infradead.org>
>>>> Cc: Dan Williams <dan.j.williams@intel.com>
>>>> Cc: Sachin Sant <sachinp@linux.vnet.ibm.com>
>>>> Cc: linux-nvdimm@lists.01.org
>>>> Cc: Ira Weiny <ira.weiny@intel.com>
>>>> Cc: Jason Gunthorpe <jgg@mellanox.com>
>>>> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
>>>> ---
>>>> mm/memremap.c | 19 +++++++++++++++----
>>>> 1 file changed, 15 insertions(+), 4 deletions(-)
>>>>
>>>> diff --git a/mm/memremap.c b/mm/memremap.c
>>>> index 73a206d0f645..d4402ff3e467 100644
>>>> --- a/mm/memremap.c
>>>> +++ b/mm/memremap.c
>>>> @@ -158,6 +158,16 @@ void memunmap_pages(struct dev_pagemap *pgmap)
>>>> {
>>>> unsigned long pfn;
>>>> int i;
>>>> + bool need_devmap_managed = false;
>>>> +
>>>> + switch (pgmap->type) {
>>>> + case MEMORY_DEVICE_PRIVATE:
>>>> + case MEMORY_DEVICE_FS_DAX:
>>>> + need_devmap_managed = true;
>>>> + break;
>>>> + default:
>>>> + break;
>>>> + }
>>>
>>> Is it overkill to avoid duplicating this switch logic in
>>> page_is_devmap_managed() by creating another call which can be used here?
>>
>> Perhaps. I can imagine a helper defined in include/linux/mm.h which
>> page_is_devmap_managed() could also call but that would impact a lot of
>> places that include mm.h. Since memremap.c already has to have intimate
>> knowledge of the pgmap->type, I think limiting the change to just what
>> is needed is better for now. So the patch looks OK to me.
>>
>> Looking at this some more, I would suggest changing devmap_managed_enable_get()
>> and devmap_managed_enable_put() to do the special case checking instead of
>> doing it in memremap_pages() and memunmap_pages().
>> Then devmap_managed_enable_get() doesn't need to return an error if
>> CONFIG_DEV_PAGEMAP_OPS isn't defined. I have only compile tested the
>> following.
>>
>> Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
>
> This looks ok as well. Can you submit it as a proper standalone patch?
>
Yes. I was just about to ask whether I should do that and you beat me to it.
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^ permalink raw reply [flat|nested] 12+ messages in thread
* [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates
@ 2020-10-23 18:32 Ralph Campbell
2020-10-24 8:19 ` Christoph Hellwig
0 siblings, 1 reply; 12+ messages in thread
From: Ralph Campbell @ 2020-10-23 18:32 UTC (permalink / raw)
To: linux-mm
Cc: Andrew Morton, Ralph Campbell, Christoph Hellwig, linux-nvdimm,
Jason Gunthorpe, Aneesh Kumar K . V, Ira
commit 6f42193fd86e ("memremap: don't use a separate devm action for
devmap_managed_enable_get") changed the static key updates such that we
now call devmap_managed_enable_put() without doing the equivalent
devmap_managed_enable_get().
devmap_managed_enable_get() is only called for MEMORY_DEVICE_PRIVATE and
MEMORY_DEVICE_FS_DAX, But memunmap_pages() get called for other pgmap
types too. This results in the below warning when switching between
system-ram and devdax mode for devdax namespace.
jump label: negative count!
WARNING: CPU: 52 PID: 1335 at kernel/jump_label.c:235 static_key_slow_try_dec+0x88/0xa0
Modules linked in:
....
NIP [c000000000433318] static_key_slow_try_dec+0x88/0xa0
LR [c000000000433314] static_key_slow_try_dec+0x84/0xa0
Call Trace:
[c000000025c1f660] [c000000000433314] static_key_slow_try_dec+0x84/0xa0
[c000000025c1f6d0] [c000000000433664] __static_key_slow_dec_cpuslocked+0x34/0xd0
[c000000025c1f700] [c0000000004337a4] static_key_slow_dec+0x54/0xf0
[c000000025c1f770] [c00000000059c49c] memunmap_pages+0x36c/0x500
[c000000025c1f820] [c000000000d91d10] devm_action_release+0x30/0x50
[c000000025c1f840] [c000000000d92e34] release_nodes+0x2f4/0x3e0
[c000000025c1f8f0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
[c000000025c1f930] [c000000000d883a4] bus_remove_device+0x124/0x210
[c000000025c1f9b0] [c000000000d80ef4] device_del+0x1d4/0x530
[c000000025c1fa70] [c000000000e341e8] unregister_dev_dax+0x48/0xe0
[c000000025c1fae0] [c000000000d91d10] devm_action_release+0x30/0x50
[c000000025c1fb00] [c000000000d92e34] release_nodes+0x2f4/0x3e0
[c000000025c1fbb0] [c000000000d8b15c] device_release_driver_internal+0x17c/0x280
[c000000025c1fbf0] [c000000000d87000] unbind_store+0x130/0x170
[c000000025c1fc30] [c000000000d862a0] drv_attr_store+0x40/0x60
[c000000025c1fc50] [c0000000006d316c] sysfs_kf_write+0x6c/0xb0
[c000000025c1fc90] [c0000000006d2328] kernfs_fop_write+0x118/0x280
[c000000025c1fce0] [c0000000005a79f8] vfs_write+0xe8/0x2a0
[c000000025c1fd30] [c0000000005a7d94] ksys_write+0x84/0x140
[c000000025c1fd80] [c00000000003a430] system_call_exception+0x120/0x270
[c000000025c1fe20] [c00000000000c540] system_call_common+0xf0/0x27c
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: linux-nvdimm@lists.01.org
Cc: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Ralph Campbell <rcampbell@nvidia.com>
Reported-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Reviewed-by: Ira Weiny <ira.weiny@intel.com>
Tested-by: Sachin Sant <sachinp@linux.vnet.ibm.com>
---
Andrew, I guess this is for the merge window since it fixes a top-of-tree
problem.
mm/memremap.c | 39 ++++++++++++++++-----------------------
1 file changed, 16 insertions(+), 23 deletions(-)
diff --git a/mm/memremap.c b/mm/memremap.c
index 73a206d0f645..16b2fb482da1 100644
--- a/mm/memremap.c
+++ b/mm/memremap.c
@@ -41,28 +41,24 @@ EXPORT_SYMBOL_GPL(memremap_compat_align);
DEFINE_STATIC_KEY_FALSE(devmap_managed_key);
EXPORT_SYMBOL(devmap_managed_key);
-static void devmap_managed_enable_put(void)
+static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
{
- static_branch_dec(&devmap_managed_key);
+ if (pgmap->type == MEMORY_DEVICE_PRIVATE ||
+ pgmap->type == MEMORY_DEVICE_FS_DAX)
+ static_branch_dec(&devmap_managed_key);
}
-static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
+static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
{
- if (pgmap->type == MEMORY_DEVICE_PRIVATE &&
- (!pgmap->ops || !pgmap->ops->page_free)) {
- WARN(1, "Missing page_free method\n");
- return -EINVAL;
- }
-
- static_branch_inc(&devmap_managed_key);
- return 0;
+ if (pgmap->type == MEMORY_DEVICE_PRIVATE ||
+ pgmap->type == MEMORY_DEVICE_FS_DAX)
+ static_branch_inc(&devmap_managed_key);
}
#else
-static int devmap_managed_enable_get(struct dev_pagemap *pgmap)
+static void devmap_managed_enable_get(struct dev_pagemap *pgmap)
{
- return -EINVAL;
}
-static void devmap_managed_enable_put(void)
+static void devmap_managed_enable_put(struct dev_pagemap *pgmap)
{
}
#endif /* CONFIG_DEV_PAGEMAP_OPS */
@@ -169,7 +165,7 @@ void memunmap_pages(struct dev_pagemap *pgmap)
pageunmap_range(pgmap, i);
WARN_ONCE(pgmap->altmap.alloc, "failed to free all reserved pages\n");
- devmap_managed_enable_put();
+ devmap_managed_enable_put(pgmap);
}
EXPORT_SYMBOL_GPL(memunmap_pages);
@@ -307,7 +303,6 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
.pgprot = PAGE_KERNEL,
};
const int nr_range = pgmap->nr_range;
- bool need_devmap_managed = true;
int error, i;
if (WARN_ONCE(!nr_range, "nr_range must be specified\n"))
@@ -323,6 +318,10 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
WARN(1, "Missing migrate_to_ram method\n");
return ERR_PTR(-EINVAL);
}
+ if (!pgmap->ops->page_free) {
+ WARN(1, "Missing page_free method\n");
+ return ERR_PTR(-EINVAL);
+ }
if (!pgmap->owner) {
WARN(1, "Missing owner\n");
return ERR_PTR(-EINVAL);
@@ -336,11 +335,9 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
}
break;
case MEMORY_DEVICE_GENERIC:
- need_devmap_managed = false;
break;
case MEMORY_DEVICE_PCI_P2PDMA:
params.pgprot = pgprot_noncached(params.pgprot);
- need_devmap_managed = false;
break;
default:
WARN(1, "Invalid pgmap type %d\n", pgmap->type);
@@ -364,11 +361,7 @@ void *memremap_pages(struct dev_pagemap *pgmap, int nid)
}
}
- if (need_devmap_managed) {
- error = devmap_managed_enable_get(pgmap);
- if (error)
- return ERR_PTR(error);
- }
+ devmap_managed_enable_get(pgmap);
/*
* Clear the pgmap nr_range as it will be incremented for each
--
2.20.1
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^ permalink raw reply related [flat|nested] 12+ messages in thread
* Re: [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates
2020-10-23 18:32 Ralph Campbell
@ 2020-10-24 8:19 ` Christoph Hellwig
0 siblings, 0 replies; 12+ messages in thread
From: Christoph Hellwig @ 2020-10-24 8:19 UTC (permalink / raw)
To: Ralph Campbell
Cc: linux-mm, Andrew Morton, Christoph Hellwig, linux-nvdimm,
Jason Gunthorpe, Aneesh Kumar K . V, Ira
Looks good,
Reviewed-by: Christoph Hellwig <hch@lst.de>
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^ permalink raw reply [flat|nested] 12+ messages in thread
end of thread, other threads:[~2020-10-24 8:19 UTC | newest]
Thread overview: 12+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-10-22 6:07 [PATCH] mm/mremap_pages: Fix static key devmap_managed_key updates Aneesh Kumar K.V
2020-10-22 8:34 ` Sachin Sant
2020-10-22 13:26 ` Christoph Hellwig
2020-10-22 15:41 ` Ira Weiny
2020-10-22 18:19 ` Ralph Campbell
2020-10-22 19:10 ` Ira Weiny
2020-10-23 2:52 ` Aneesh Kumar K.V
2020-10-23 6:38 ` Sachin Sant
2020-10-23 6:46 ` Christoph Hellwig
2020-10-23 17:29 ` Ralph Campbell
2020-10-23 18:32 Ralph Campbell
2020-10-24 8:19 ` Christoph Hellwig
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