6.6-stable review patch. If anyone has any objections, please let me know.
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From: Alison Schofield alison.schofield@intel.com
commit 0e33ac9c3ffe5e4f55c68345f44cea7fec2fe750 upstream.
Poison inject and clear are supported via debugfs where a privileged user can inject and clear poison to a device physical address.
Commit 458ba8189cb4 ("cxl: Add cxl_decoders_committed() helper") added a lockdep assert that highlighted a gap in poison inject and clear functions where holding the dpa_rwsem does not assure that a a DPA is not added to a region.
The impact for inject and clear is that if the DPA address being injected or cleared has been attached to a region, but not yet committed, the dev_dbg() message intended to alert the debug user that they are acting on a mapped address is not emitted. Also, the cxl_poison trace event that serves as a log of the inject and clear activity will not include region info.
Close this gap by snapshotting an unchangeable region state during poison inject and clear operations. That means holding both the region_rwsem and the dpa_rwsem during the inject and clear ops.
Fixes: d2fbc4865802 ("cxl/memdev: Add support for the Inject Poison mailbox command") Fixes: 9690b07748d1 ("cxl/memdev: Add support for the Clear Poison mailbox command") Signed-off-by: Alison Schofield alison.schofield@intel.com Reviewed-by: Davidlohr Bueso dave@stgolabs.net Reviewed-by: Dave Jiang dave.jiang@intel.com Link: https://lore.kernel.org/r/08721dc1df0a51e4e38fecd02425c3475912dfd5.170104144... Signed-off-by: Dan Williams dan.j.williams@intel.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/cxl/core/memdev.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-)
--- a/drivers/cxl/core/memdev.c +++ b/drivers/cxl/core/memdev.c @@ -331,10 +331,16 @@ int cxl_inject_poison(struct cxl_memdev if (!IS_ENABLED(CONFIG_DEBUG_FS)) return 0;
- rc = down_read_interruptible(&cxl_dpa_rwsem); + rc = down_read_interruptible(&cxl_region_rwsem); if (rc) return rc;
+ rc = down_read_interruptible(&cxl_dpa_rwsem); + if (rc) { + up_read(&cxl_region_rwsem); + return rc; + } + rc = cxl_validate_poison_dpa(cxlmd, dpa); if (rc) goto out; @@ -362,6 +368,7 @@ int cxl_inject_poison(struct cxl_memdev trace_cxl_poison(cxlmd, cxlr, &record, 0, 0, CXL_POISON_TRACE_INJECT); out: up_read(&cxl_dpa_rwsem); + up_read(&cxl_region_rwsem);
return rc; } @@ -379,10 +386,16 @@ int cxl_clear_poison(struct cxl_memdev * if (!IS_ENABLED(CONFIG_DEBUG_FS)) return 0;
- rc = down_read_interruptible(&cxl_dpa_rwsem); + rc = down_read_interruptible(&cxl_region_rwsem); if (rc) return rc;
+ rc = down_read_interruptible(&cxl_dpa_rwsem); + if (rc) { + up_read(&cxl_region_rwsem); + return rc; + } + rc = cxl_validate_poison_dpa(cxlmd, dpa); if (rc) goto out; @@ -419,6 +432,7 @@ int cxl_clear_poison(struct cxl_memdev * trace_cxl_poison(cxlmd, cxlr, &record, 0, 0, CXL_POISON_TRACE_CLEAR); out: up_read(&cxl_dpa_rwsem); + up_read(&cxl_region_rwsem);
return rc; }