linux/kernel/kexec_core.c, branch v6.16

PM: Restrict swap use to later in the suspend sequence

2025-06-26T18:39:34Z

Currently swap is restricted before drivers have had a chance to do their prepare() PM callbacks. Restricting swap this early means that if a driver needs to evict some content from memory into sawp in it's prepare callback, it won't be able to. On AMD dGPUs this can lead to failed suspends under memory pressure situations as all VRAM must be evicted to system memory or swap. Move the swap restriction to right after all devices have had a chance to do the prepare() callback. If there is any problem with the sequence, restore swap in the appropriate dpm resume callbacks or error handling paths. Closes: https://github.com/ROCm/ROCK-Kernel-Driver/issues/174 Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/2362 Signed-off-by: Mario Limonciello Tested-by: Nat Wittstock Tested-by: Lucian Langa Link: https://patch.msgid.link/20250613214413.4127087-1-superm1@kernel.org Signed-off-by: Rafael J. Wysocki

kexec: define functions to map and unmap segments

2025-04-29T19:54:53Z

Implement kimage_map_segment() to enable IMA to map the measurement log list to the kimage structure during the kexec 'load' stage. This function gathers the source pages within the specified address range, and maps them to a contiguous virtual address range. This is a preparation for later usage. Implement kimage_unmap_segment() for unmapping segments using vunmap(). Cc: Eric Biederman Cc: Baoquan He Cc: Vivek Goyal Cc: Dave Young Co-developed-by: Tushar Sugandhi Signed-off-by: Tushar Sugandhi Signed-off-by: Steven Chen Acked-by: Baoquan He Tested-by: Stefan Berger # ppc64/kvm Signed-off-by: Mimi Zohar

Merge tag 'mm-nonmm-stable-2025-03-30-18-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2025-04-01T17:06:52Z

Pull non-MM updates from Andrew Morton: - The series "powerpc/crash: use generic crashkernel reservation" from Sourabh Jain changes powerpc's kexec code to use more of the generic layers. - The series "get_maintainer: report subsystem status separately" from Vlastimil Babka makes some long-requested improvements to the get_maintainer output. - The series "ucount: Simplify refcounting with rcuref_t" from Sebastian Siewior cleans up and optimizing the refcounting in the ucount code. - The series "reboot: support runtime configuration of emergency hw_protection action" from Ahmad Fatoum improves the ability for a driver to perform an emergency system shutdown or reboot. - The series "Converge on using secs_to_jiffies() part two" from Easwar Hariharan performs further migrations from msecs_to_jiffies() to secs_to_jiffies(). - The series "lib/interval_tree: add some test cases and cleanup" from Wei Yang permits more userspace testing of kernel library code, adds some more tests and performs some cleanups. - The series "hung_task: Dump the blocking task stacktrace" from Masami Hiramatsu arranges for the hung_task detector to dump the stack of the blocking task and not just that of the blocked task. - The series "resource: Split and use DEFINE_RES*() macros" from Andy Shevchenko provides some cleanups to the resource definition macros. - Plus the usual shower of singleton patches - please see the individual changelogs for details. * tag 'mm-nonmm-stable-2025-03-30-18-23' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (77 commits) mailmap: consolidate email addresses of Alexander Sverdlin fs/procfs: fix the comment above proc_pid_wchan() relay: use kasprintf() instead of fixed buffer formatting resource: replace open coded variant of DEFINE_RES() resource: replace open coded variants of DEFINE_RES_*_NAMED() resource: replace open coded variant of DEFINE_RES_NAMED_DESC() resource: split DEFINE_RES_NAMED_DESC() out of DEFINE_RES_NAMED() samples: add hung_task detector mutex blocking sample hung_task: show the blocker task if the task is hung on mutex kexec_core: accept unaccepted kexec segments' destination addresses watchdog/perf: optimize bytes copied and remove manual NUL-termination lib/interval_tree: fix the comment of interval_tree_span_iter_next_gap() lib/interval_tree: skip the check before go to the right subtree lib/interval_tree: add test case for span iteration lib/interval_tree: add test case for interval_tree_iter_xxx() helpers lib/rbtree: add random seed lib/rbtree: split tests lib/rbtree: enable userland test suite for rbtree related data structure checkpatch: describe --min-conf-desc-length scripts/gdb/symbols: determine KASLR offset on s390 ...

Merge tag 'printk-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux

2025-03-28T02:22:24Z

Pull printk updates from Petr Mladek: - New option "printk.debug_non_panic_cpus" allows to store printk messages from non-panic CPUs during panic. It might be useful when panic() fails. It is disabled by default because it increases the chance to see the messages printed before panic() and on the panic-CPU. - New build option "CONFIG_NULL_TTY_DEFAULT_CONSOLE" allows to build kernel without the virtual terminal support which prefers ttynull over serial console. - Do not unblank suspended consoles. - Some code clean up. * tag 'printk-for-6.15' of git://git.kernel.org/pub/scm/linux/kernel/git/printk/linux: printk/panic: Add option to allow non-panic CPUs to write to the ring buffer. printk: Add an option to allow ttynull to be a default console device printk: Check CON_SUSPEND when unblanking a console printk: Rename console_start to console_resume printk: Rename console_stop to console_suspend printk: Rename resume_console to console_resume_all printk: Rename suspend_console to console_suspend_all

kexec_core: accept unaccepted kexec segments' destination addresses

2025-03-17T19:17:01Z

The UEFI Specification version 2.9 introduces the concept of memory acceptance: some Virtual Machine platforms, such as Intel TDX or AMD SEV-SNP, require memory to be accepted before it can be used by the guest. Accepting memory is expensive. The memory must be allocated by the VMM and then brought to a known safe state: cache must be flushed, memory must be zeroed with the guest's encryption key, and associated metadata must be manipulated. These operations must be performed from a trusted environment (firmware or TDX module). Switching context to and from it also takes time. This cost adds up. On large confidential VMs, memory acceptance alone can take minutes. It is better to delay memory acceptance until the memory is actually needed. The kernel accepts memory when it is allocated from buddy allocator for the first time. This reduces boot time and decreases memory overhead as the VMM can allocate memory as needed. It does not work when the guest attempts to kexec into a new kernel. The kexec segments' destination addresses are not allocated by the buddy allocator. Instead, they are searched from normal system RAM (top-down or bottom-up) and exclude driver-managed memory, ACPI, persistent, and reserved memory. Unaccepted memory is normal system RAM from kernel point of view and kexec can place segments there. Kexec bypasses the code path in buddy allocator where memory gets accepted and it leads to a crash when kexec accesses segments' memory. Accept the destination addresses during the kexec load, immediately after they pass sanity checks. This ensures the code is located in a common place shared by both the kexec_load and kexec_file_load system calls. This will not conflict with the accounting in try_to_accept_memory_one() since the accounting is set during kernel boot and decremented when pages are moved to the freelists. There is no harm in invoking accept_memory() on a page before making it available to the buddy allocator. No need to worry about re-accepting memory since accept_memory() checks the unaccepted bitmap before accepting a memory page. Although a user may perform kexec loading without ever triggering the jump, it doesn't impact much since kexec loading is not in a performance-critical path. Additionally, the destination addresses are always searched and found in the same location on a given system. Changes to the destination address searching logic to locate only memory in either unaccepted or accepted status are unnecessary and complicated. [kirill.shutemov@linux.intel.com: update the commit message] Link: https://lkml.kernel.org/r/20250307084411.2150367-1-kirill.shutemov@linux.intel.com Signed-off-by: Yan Zhao Signed-off-by: Kirill A. Shutemov Acked-by: Dave Hansen Cc: "Eric W. Biederman" Cc: Ashish Kalra Cc: Baoquan He Cc: Jianxiong Gao Signed-off-by: Andrew Morton

printk: Rename resume_console to console_resume_all

2025-03-11T10:51:27Z

The function resume_console has a misleading name, since it resumes all consoles, so rename it accordingly. Signed-off-by: Marcos Paulo de Souza Reviewed-by: Petr Mladek Reviewed-by: John Ogness Link: https://lore.kernel.org/r/20250226-printk-renaming-v1-2-0b878577f2e6@suse.com [pmladek@suse.com: Fixed typo in the commit message.] Signed-off-by: Petr Mladek

printk: Rename suspend_console to console_suspend_all

2025-03-11T10:49:34Z

The function suspend_console has a misleading name, since it suspends all consoles, so rename it accordingly. Signed-off-by: Marcos Paulo de Souza Reviewed-by: Petr Mladek Reviewed-by: John Ogness Link: https://lore.kernel.org/r/20250226-printk-renaming-v1-1-0b878577f2e6@suse.com [pmladek@suse.com: Fixed typo in the commit message.] Signed-off-by: Petr Mladek

treewide: const qualify ctl_tables where applicable

2025-01-28T12:48:37Z

Add the const qualifier to all the ctl_tables in the tree except for watchdog_hardlockup_sysctl, memory_allocation_profiling_sysctls, loadpin_sysctl_table and the ones calling register_net_sysctl (./net, drivers/inifiniband dirs). These are special cases as they use a registration function with a non-const qualified ctl_table argument or modify the arrays before passing them on to the registration function. Constifying ctl_table structs will prevent the modification of proc_handler function pointers as the arrays would reside in .rodata. This is made possible after commit 78eb4ea25cd5 ("sysctl: treewide: constify the ctl_table argument of proc_handlers") constified all the proc_handlers. Created this by running an spatch followed by a sed command: Spatch: virtual patch @ depends on !(file in "net") disable optional_qualifier @ identifier table_name != { watchdog_hardlockup_sysctl, iwcm_ctl_table, ucma_ctl_table, memory_allocation_profiling_sysctls, loadpin_sysctl_table }; @@ + const struct ctl_table table_name [] = { ... }; sed: sed --in-place \ -e "s/struct ctl_table .table = &uts_kern/const struct ctl_table *table = \&uts_kern/" \ kernel/utsname_sysctl.c Reviewed-by: Song Liu Acked-by: Steven Rostedt (Google) # for kernel/trace/ Reviewed-by: Martin K. Petersen # SCSI Reviewed-by: Darrick J. Wong # xfs Acked-by: Jani Nikula Acked-by: Corey Minyard Acked-by: Wei Liu Acked-by: Thomas Gleixner Reviewed-by: Bill O'Donnell Acked-by: Baoquan He Acked-by: Ashutosh Dixit Acked-by: Anna Schumaker Signed-off-by: Joel Granados

kexec_core: Add and update comments regarding the KEXEC_JUMP flow

2025-01-14T12:03:34Z

The KEXEC_JUMP flow is analogous to hibernation flows occurring before and after creating an image and before and after jumping from the restore kernel to the image one, which is why it uses the same device callbacks as those hibernation flows. Add comments explaining that to the code in question and update an existing comment in it which appears a bit out of context. No functional changes. Signed-off-by: Rafael J. Wysocki Signed-off-by: David Woodhouse Signed-off-by: Borislav Petkov (AMD) Link: https://lore.kernel.org/r/20250109140757.2841269-8-dwmw2@infradead.org

sysctl: treewide: constify the ctl_table argument of proc_handlers

2024-07-24T18:59:29Z

const qualify the struct ctl_table argument in the proc_handler function signatures. This is a prerequisite to moving the static ctl_table structs into .rodata data which will ensure that proc_handler function pointers cannot be modified. This patch has been generated by the following coccinelle script: ``` virtual patch @r1@ identifier ctl, write, buffer, lenp, ppos; identifier func !~ "appldata_(timer|interval)_handler|sched_(rt|rr)_handler|rds_tcp_skbuf_handler|proc_sctp_do_(hmac_alg|rto_min|rto_max|udp_port|alpha_beta|auth|probe_interval)"; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int write, void *buffer, size_t *lenp, loff_t *ppos); @r2@ identifier func, ctl, write, buffer, lenp, ppos; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int write, void *buffer, size_t *lenp, loff_t *ppos) { ... } @r3@ identifier func; @@ int func( - struct ctl_table * + const struct ctl_table * ,int , void *, size_t *, loff_t *); @r4@ identifier func, ctl; @@ int func( - struct ctl_table *ctl + const struct ctl_table *ctl ,int , void *, size_t *, loff_t *); @r5@ identifier func, write, buffer, lenp, ppos; @@ int func( - struct ctl_table * + const struct ctl_table * ,int write, void *buffer, size_t *lenp, loff_t *ppos); ``` * Code formatting was adjusted in xfs_sysctl.c to comply with code conventions. The xfs_stats_clear_proc_handler, xfs_panic_mask_proc_handler and xfs_deprecated_dointvec_minmax where adjusted. * The ctl_table argument in proc_watchdog_common was const qualified. This is called from a proc_handler itself and is calling back into another proc_handler, making it necessary to change it as part of the proc_handler migration. Co-developed-by: Thomas Weißschuh Signed-off-by: Thomas Weißschuh Co-developed-by: Joel Granados Signed-off-by: Joel Granados