On Tue, Jun 09, 2026 at 01:02:00AM -0700, Allison Henderson wrote:

On Mon, 2026-06-08 at 02:32 -0700, Breno Leitao wrote:

quoted

rds_info_getsockopt() pins the destination user pages with FOLL_WRITE and
the RDS_INFO_* producers memcpy the snapshot into them through
kmap_atomic(). Because that copy goes through the kernel direct map, the
dirty bit on the user PTE is never set, so unpin_user_pages() releases the
pages without marking them dirty. A file-backed destination page can then
be reclaimed without writeback, silently discarding the copied data.

Use unpin_user_pages_dirty_lock() with make_dirty=true so the modified
pages are marked dirty before they are unpinned.

Fixes: a8c879a7ee98 ("RDS: Info and stats")
Signed-off-by: Breno Leitao <leitao@debian.org>

Hi Breno,

Thanks for adding the Fixes tag. One thing though: now that this is
standalone, it collides with "[PATCH net-next v3 2/2] rds: convert to
getsockopt_iter" since both rewrite the same unpin in the out: block of
rds_info_getsockopt().  

Easiest on everyone is to just keep it folded into the net-next series as
a three-patch set, rather than splitting the fix out to net.

I got from the maintainers that they want to continue to split the fixes
into net and non fixes (features) into net-next.

	"So just prepare for net with Fixes tags and we'll route the
	patches accordingly." -- Jakub

https://lore.kernel.org/all/20260527155942.45c43c8d@kernel.org/ (local)

Thanks for the review,
--breno