[Bug 2144914] Re: Noble kernel 6.8.0-108 does not compile when KASAN enabled

** Tags added: kernel-daily-bug

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Title:
Noble kernel 6.8.0-108 does not compile when KASAN enabled

Status in linux package in Ubuntu:
Invalid
Status in linux source package in Noble:
In Progress

Bug description:
[ Impact ]

When trying to compile Noble's kernel 6.8.0-108 with KASAN enabled the
following compile-time error appeared:

/build/noble/mm/kasan/common.c: In function '__kasan_unpoison_vmap_areas':
/build/noble/mm/kasan/common.c:566:34: error: 'KASAN_VMALLOC_KEEP_TAG' undeclared (first use in this function); did you mean 'KASAN_VMALLOC_INIT'?
566 | if (WARN_ON_ONCE(flags & KASAN_VMALLOC_KEEP_TAG))
| ^~~~~~~~~~~~~~~~~~~~~~
/build/noble/include/asm-generic/bug.h:111:32: note: in definition of macro 'WARN_ON_ONCE'
111 | int __ret_warn_on = !!(condition); \
| ^~~~~~~~~
/build/noble/mm/kasan/common.c:566:34: note: each undeclared identifier is reported only once for each function it appears in
566 | if (WARN_ON_ONCE(flags & KASAN_VMALLOC_KEEP_TAG))
| ^~~~~~~~~~~~~~~~~~~~~~
/build/noble/include/asm-generic/bug.h:111:32: note: in definition of macro 'WARN_ON_ONCE'
111 | int __ret_warn_on = !!(condition); \
| ^~~~~~~~~
CC [M] samples/ftrace/ftrace-direct-too.o


[ Fix ]

The error is due to an upstream stable update which missed the very first commit of the patchset:
- https://lore.kernel.org/all/a2a1889754be3d97b8919cb2d3d099d12461f814.1765978969.git.m.wieczorretman@pm.me/T/#u

To fix it, it is necessary to backport
- 007f5da43b3d ("mm/kasan: fix incorrect unpoisoning in vrealloc for KASAN").

[ Test Case ]

Compile the kernel with KASAN enabled.

[ Regression Potential ]

No regression potential. The kernel is already
not compiling with kasan enabled.
The fix allows the kernel to compile correctly.

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