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| author | Dan Williams <dan.j.williams@intel.com> | 2023-01-25 23:23:46 +0300 |
|---|---|---|
| committer | Dan Williams <dan.j.williams@intel.com> | 2023-01-29 02:32:36 +0300 |
| commit | c91d713630848460de8669e6570307b7e559863b (patch) | |
| tree | feeb34b196684b0b3f1ba09cacadc03ed93a920d /drivers/nvdimm/Kconfig | |
| parent | fb6df4366f86dd252bfa3049edffa52d17e7b895 (diff) | |
| download | linux-c91d713630848460de8669e6570307b7e559863b.tar.xz | |
nvdimm: Support sizeof(struct page) > MAX_STRUCT_PAGE_SIZE
Commit 6e9f05dc66f9 ("libnvdimm/pfn_dev: increase MAX_STRUCT_PAGE_SIZE")
...updated MAX_STRUCT_PAGE_SIZE to account for sizeof(struct page)
potentially doubling in the case of CONFIG_KMSAN=y. Unfortunately this
doubles the amount of capacity stolen from user addressable capacity for
everyone, regardless of whether they are using the debug option. Revert
that change, mandate that MAX_STRUCT_PAGE_SIZE never exceed 64, but
allow for debug scenarios to proceed with creating debug sized page maps
with a compile option to support debug scenarios.
Note that this only applies to cases where the page map is permanent,
i.e. stored in a reservation of the pmem itself ("--map=dev" in "ndctl
create-namespace" terms). For the "--map=mem" case, since the allocation
is ephemeral for the lifespan of the namespace, there are no explicit
restriction. However, the implicit restriction, of having enough
available "System RAM" to store the page map for the typically large
pmem, still applies.
Fixes: 6e9f05dc66f9 ("libnvdimm/pfn_dev: increase MAX_STRUCT_PAGE_SIZE")
Cc: <stable@vger.kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Marco Elver <elver@google.com>
Reported-by: Jeff Moyer <jmoyer@redhat.com>
Acked-by: Yu Zhao <yuzhao@google.com>
Link: https://lore.kernel.org/r/167467815773.463042.7022545814443036382.stgit@dwillia2-xfh.jf.intel.com
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Diffstat (limited to 'drivers/nvdimm/Kconfig')
| -rw-r--r-- | drivers/nvdimm/Kconfig | 19 |
1 files changed, 19 insertions, 0 deletions
diff --git a/drivers/nvdimm/Kconfig b/drivers/nvdimm/Kconfig index 79d93126453d..77b06d54cc62 100644 --- a/drivers/nvdimm/Kconfig +++ b/drivers/nvdimm/Kconfig @@ -102,6 +102,25 @@ config NVDIMM_KEYS depends on ENCRYPTED_KEYS depends on (LIBNVDIMM=ENCRYPTED_KEYS) || LIBNVDIMM=m +config NVDIMM_KMSAN + bool + depends on KMSAN + help + KMSAN, and other memory debug facilities, increase the size of + 'struct page' to contain extra metadata. This collides with + the NVDIMM capability to store a potentially + larger-than-"System RAM" size 'struct page' array in a + reservation of persistent memory rather than limited / + precious DRAM. However, that reservation needs to persist for + the life of the given NVDIMM namespace. If you are using KMSAN + to debug an issue unrelated to NVDIMMs or DAX then say N to this + option. Otherwise, say Y but understand that any namespaces + (with the page array stored pmem) created with this build of + the kernel will permanently reserve and strand excess + capacity compared to the CONFIG_KMSAN=n case. + + Select N if unsure. + config NVDIMM_TEST_BUILD tristate "Build the unit test core" depends on m |