The patch below does not apply to the 6.17-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.17.y git checkout FETCH_HEAD git cherry-pick -x f4d027921c811ff7fc16e4d03c6bbbf4347cf37a # <resolve conflicts, build, test, etc.> git commit -s git send-email --to 'stable@vger.kernel.org' --in-reply-to '2025102001-outsmart-slackness-607a@gregkh' --subject-prefix 'PATCH 6.17.y' HEAD^..

Possible dependencies:

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From f4d027921c811ff7fc16e4d03c6bbbf4347cf37a Mon Sep 17 00:00:00 2001 From: Dave Jiang dave.jiang@intel.com Date: Fri, 10 Oct 2025 13:57:55 -0700 Subject: [PATCH] cxl: Fix match_region_by_range() to use region_res_match_cxl_range()

match_region_by_range() is not using the helper function that also takes extended linear cache size into account when comparing regions. This causes a x2 region to show up as 2 partial incomplete regions rather than a single CXL region with extended linear cache support. Replace the open coded compare logic with the proper helper function for comparison. User visible impact is that when 'cxl list' is issued, no activa CXL region(s) are shown. There may be multiple idle regions present. No actual active CXL region is present in the kernel.

[dj: Fix stable address]

Fixes: 0ec9849b6333 ("acpi/hmat / cxl: Add extended linear cache support for CXL") Cc: stable@vger.kernel.org Reviewed-by: Gregory Price gourry@gourry.net Reviewed-by: Alison Schofield alison.schofield@intel.com Reviewed-by: Dan Williams dan.j.williams@intel.com Signed-off-by: Dave Jiang dave.jiang@intel.com

diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c index 858d4678628d..57ed85e332d3 100644 --- a/drivers/cxl/core/region.c +++ b/drivers/cxl/core/region.c @@ -3398,10 +3398,7 @@ static int match_region_by_range(struct device *dev, const void *data) p = &cxlr->params;

guard(rwsem_read)(&cxl_rwsem.region); - if (p->res && p->res->start == r->start && p->res->end == r->end) - return 1; - - return 0; + return region_res_match_cxl_range(p, r); }

static int cxl_extended_linear_cache_resize(struct cxl_region *cxlr,