Re: [PATCH v3] mm/migrate: Fix do_pages_stat in 32-bit mode
From: David Hildenbrand
Date: Tue Jul 01 2025 - 14:17:28 EST
On 01.07.25 19:55, Christoph Berg wrote:
Re: Zi Yan
Fixes should be:
Fixes: 5b1b561ba73c ("mm: simplify compat_sys_move_pages")
Closes could be a link to the bug report.
Updated, thanks.
This seems to work, but honestly I am wondering, if copy_from_user
needs a special 32-bit case, doesn't copy_to_user need special casing
as well?
Scratch that, it works because an int[] is copied back, and that's
always the same size.
So I think the patch is good to go.
Christoph
If you have to resend, next time resend the full patch separately, not
as reply to the previous version.
From 426c93d558572248273cf386ca784626ae431413 Mon Sep 17 00:00:00 2001
From: Christoph Berg <myon@xxxxxxxxxx>
Date: Tue, 24 Jun 2025 16:44:27 +0200
Subject: [PATCH v3] mm/migrate: Fix do_pages_stat in 32-bit mode
s/32-bit mode/compat mode/ ?
Because on native 32bit it should be working fine.
For arrays with more than 16 entries, the old code would incorrectly
advance the pages pointer by 16 words instead of 16 compat_uptr_t.
Fix by doing the pointer arithmetic inside get_compat_pages_array where
pages32 is already a correctly-typed pointer.
Discovered while working on PostgreSQL 18's new NUMA introspection code.
Signed-off-by: Christoph Berg <myon@xxxxxxxxxx>
Suggested-by: David Hildenbrand <david@xxxxxxxxxx>
Fixes: 5b1b561ba73c ("mm: simplify compat_sys_move_pages")
Hmm, still not sure if 5b1b561ba73c really introduced the issue. I think
it only messed with the "pages" pointer, not with the "status" pointer?
Hmmmm
I assume we want to Cc stable. @Andrew can do that.
Reported-by: Bertrand Drouvot <bertranddrouvot.pg@xxxxxxxxx>
Reported-by: Tomas Vondra <tomas@xxxxxxxxx>
Closes: https://www.postgresql.org/message-id/flat/6342f601-77de-4ee0-8c2a-3deb50ceac5b%40vondra.me#86402e3d80c031788f5f55b42c459471
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Acked-by: David Hildenbrand <david@xxxxxxxxxx>
--
Cheers,
David / dhildenb