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12b9a2c05d
Currently, when restoring higher order folios, kho_restore_folio() only
calls prep_compound_page() on all the pages. That is not enough to
properly initialize the folios. The managed page count does not get
updated, the reserved flag does not get dropped, and page count does not
get initialized properly.
Restoring a higher order folio with it results in the following BUG with
CONFIG_DEBUG_VM when attempting to free the folio:
BUG: Bad page state in process test pfn:104e2b
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0xffffffffffffffff pfn:0x104e2b
flags: 0x2fffff80000000(node=0|zone=2|lastcpupid=0x1fffff)
raw: 002fffff80000000 0000000000000000 00000000ffffffff 0000000000000000
raw: ffffffffffffffff 0000000000000000 00000001ffffffff 0000000000000000
page dumped because: nonzero _refcount
[...]
Call Trace:
<TASK>
dump_stack_lvl+0x4b/0x70
bad_page.cold+0x97/0xb2
__free_frozen_pages+0x616/0x850
[...]
Combine the path for 0-order and higher order folios, initialize the tail
pages with a count of zero, and call adjust_managed_page_count() to
account for all the pages instead of just missing them.
In addition, since all the KHO-preserved pages get marked with
MEMBLOCK_RSRV_NOINIT by deserialize_bitmap(), the reserved flag is not
actually set (as can also be seen from the flags of the dumped page in the
logs above). So drop the ClearPageReserved() calls.
[ptyadav@amazon.de: declare i in the loop instead of at the top]
Link: https://lkml.kernel.org/r/20250613125916.39272-1-pratyush@kernel.org
Link: https://lkml.kernel.org/r/20250605171143.76963-1-pratyush@kernel.org
Fixes:
|
||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .pylintrc | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.