Patch "x86/numa: Fix the sort compare func used in numa_fill_memblks()" has been added to the 6.6-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    x86/numa: Fix the sort compare func used in numa_fill_memblks()

to the 6.6-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     x86-numa-fix-the-sort-compare-func-used-in-numa_fill.patch
and it can be found in the queue-6.6 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 2deb95cbf2fdd0daee565d05a089ef519f625961
Author: Alison Schofield <alison.schofield@xxxxxxxxx>
Date:   Fri Jan 12 12:09:51 2024 -0800

    x86/numa: Fix the sort compare func used in numa_fill_memblks()
    
    [ Upstream commit b626070ffc14acca5b87a2aa5f581db98617584c ]
    
    The compare function used to sort memblks into starting address
    order fails when the result of its u64 address subtraction gets
    truncated to an int upon return.
    
    The impact of the bad sort is that memblks will be filled out
    incorrectly. Depending on the set of memblks, a user may see no
    errors at all but still have a bad fill, or see messages reporting
    a node overlap that leads to numa init failure:
    
    [] node 0 [mem: ] overlaps with node 1 [mem: ]
    [] No NUMA configuration found
    
    Replace with a comparison that can only result in: 1, 0, -1.
    
    Fixes: 8f012db27c95 ("x86/numa: Introduce numa_fill_memblks()")
    Signed-off-by: Alison Schofield <alison.schofield@xxxxxxxxx>
    Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
    Reviewed-by: Dan Williams <dan.j.williams@xxxxxxxxx>
    Link: https://lore.kernel.org/r/99dcb3ae87e04995e9f293f6158dc8fa0749a487.1705085543.git.alison.schofield@xxxxxxxxx
    Signed-off-by: Dan Williams <dan.j.williams@xxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/arch/x86/mm/numa.c b/arch/x86/mm/numa.c
index e60c61b8bbc61..dae5c952735c7 100644
--- a/arch/x86/mm/numa.c
+++ b/arch/x86/mm/numa.c
@@ -961,7 +961,7 @@ static int __init cmp_memblk(const void *a, const void *b)
 	const struct numa_memblk *ma = *(const struct numa_memblk **)a;
 	const struct numa_memblk *mb = *(const struct numa_memblk **)b;
 
-	return ma->start - mb->start;
+	return (ma->start > mb->start) - (ma->start < mb->start);
 }
 
 static struct numa_memblk *numa_memblk_list[NR_NODE_MEMBLKS] __initdata;