kernel/linux.git/fs/proc/vmcore.c, branch v6.12.80

fs/proc: fix softlockup in __read_vmcore (part 2)

2025-01-23T16:23:01+00:00

commit cbc5dde0a461240046e8a41c43d7c3b76d5db952 upstream. Since commit 5cbcb62dddf5 ("fs/proc: fix softlockup in __read_vmcore") the number of softlockups in __read_vmcore at kdump time have gone down, but they still happen sometimes. In a memory constrained environment like the kdump image, a softlockup is not just a harmless message, but it can interfere with things like RCU freeing memory, causing the crashdump to get stuck. The second loop in __read_vmcore has a lot more opportunities for natural sleep points, like scheduling out while waiting for a data write to happen, but apparently that is not always enough. Add a cond_resched() to the second loop in __read_vmcore to (hopefully) get rid of the softlockups. Link: https://lkml.kernel.org/r/20250110102821.2a37581b@fangorn Fixes: 5cbcb62dddf5 ("fs/proc: fix softlockup in __read_vmcore") Signed-off-by: Rik van Riel Reported-by: Breno Leitao Cc: Baoquan He Cc: Dave Young Cc: Vivek Goyal Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

fs/proc: fix compile warning about variable 'vmcore_mmap_ops'

2024-11-07T22:14:59+00:00

When build with !CONFIG_MMU, the variable 'vmcore_mmap_ops' is defined but not used: >> fs/proc/vmcore.c:458:42: warning: unused variable 'vmcore_mmap_ops' 458 | static const struct vm_operations_struct vmcore_mmap_ops = { Fix this by only defining it when CONFIG_MMU is enabled. Link: https://lkml.kernel.org/r/20241101034803.9298-1-xiqi2@huawei.com Fixes: 9cb218131de1 ("vmcore: introduce remap_oldmem_pfn_range()") Signed-off-by: Qi Xi Reported-by: kernel test robot Closes: https://lore.kernel.org/lkml/202410301936.GcE8yUos-lkp@intel.com/ Cc: Baoquan He Cc: Dave Young Cc: Michael Holzheu Cc: Vivek Goyal Cc: Wang ShaoBo Signed-off-by: Andrew Morton

fs/proc: fix softlockup in __read_vmcore

2024-05-11T22:51:44+00:00

While taking a kernel core dump with makedumpfile on a larger system, softlockup messages often appear. While softlockup warnings can be harmless, they can also interfere with things like RCU freeing memory, which can be problematic when the kdump kexec image is configured with as little memory as possible. Avoid the softlockup, and give things like work items and RCU a chance to do their thing during __read_vmcore by adding a cond_resched. Link: https://lkml.kernel.org/r/20240507091858.36ff767f@imladris.surriel.com Signed-off-by: Rik van Riel Acked-by: Baoquan He Cc: Dave Young Cc: Vivek Goyal Cc: Signed-off-by: Andrew Morton

vmcore: replace strncpy with strscpy_pad

2024-04-26T04:07:06+00:00

strncpy() is in the process of being replaced as it is deprecated [1]. We should move towards safer and less ambiguous string interfaces. Looking at vmcoredd_header's definition: | struct vmcoredd_header { | __u32 n_namesz; /* Name size */ | __u32 n_descsz; /* Content size */ | __u32 n_type; /* NT_VMCOREDD */ | __u8 name[8]; /* LINUX\0\0\0 */ | __u8 dump_name[VMCOREDD_MAX_NAME_BYTES]; /* Device dump's name */ | }; .. we see that @name wants to be NUL-padded. We're copying data->dump_name which is defined as: | char dump_name[VMCOREDD_MAX_NAME_BYTES]; /* Unique name of the dump */ .. which shares the same size as vdd_hdr->dump_name. Let's make sure we NUL-pad this as well. Use strscpy_pad() which NUL-terminates and NUL-pads its destination buffers. Specifically, use the new 2-argument version of strscpy_pad introduced in Commit e6584c3964f2f ("string: Allow 2-argument strscpy()"). Link: https://www.kernel.org/doc/html/latest/process/deprecated.html#strncpy-on-nul-terminated-strings [1] Link: https://github.com/KSPP/linux/issues/90 Link: https://lkml.kernel.org/r/20240401-strncpy-fs-proc-vmcore-c-v2-1-dd0a73f42635@google.com Signed-off-by: Justin Stitt Acked-by: Baoquan He Cc: Dave Young Cc: Vivek Goyal Signed-off-by: Andrew Morton

proc/vmcore: fix signedness bug in read_from_oldmem()

2023-07-27T20:07:05+00:00

The bug is the error handling: if (tmp < nr_bytes) { "tmp" can hold negative error codes but because "nr_bytes" is type size_t the negative error codes are treated as very high positive values (success). Fix this by changing "nr_bytes" to type ssize_t. The "nr_bytes" variable is used to store values between 1 and PAGE_SIZE and they can fit in ssize_t without any issue. Link: https://lkml.kernel.org/r/b55f7eed-1c65-4adc-95d1-6c7c65a54a6e@moroto.mountain Fixes: 5d8de293c224 ("vmcore: convert copy_oldmem_page() to take an iov_iter") Signed-off-by: Dan Carpenter Reviewed-by: Matthew Wilcox (Oracle) Acked-by: Baoquan He Cc: Dave Young Cc: Vivek Goyal Cc: Alexey Dobriyan Cc: Signed-off-by: Andrew Morton

coredump, vmcore: Set p_align to 4 for PT_NOTE

2023-05-16T21:32:00+00:00

Tools like readelf/llvm-readelf use p_align to parse a PT_NOTE program header as an array of 4-byte entries or 8-byte entries. Currently, there are workarounds[1] in place for Linux to treat p_align==0 as 4. However, it would be more appropriate to set the correct alignment so that tools do not have to rely on guesswork. FreeBSD coredumps set p_align to 4 as well. [1]: https://sourceware.org/git/?p=binutils-gdb.git;a=commit;h=82ed9683ec099d8205dc499ac84febc975235af6 [2]: https://reviews.llvm.org/D150022 Signed-off-by: Fangrui Song Signed-off-by: Kees Cook Link: https://lore.kernel.org/r/20230512022528.3430327-1-maskray@google.com

ELF: fix all "Elf" typos

2023-04-08T20:45:37+00:00

ELF is acronym and therefore should be spelled in all caps. I left one exception at Documentation/arm/nwfpe/nwfpe.rst which looks like being written in the first person. Link: https://lkml.kernel.org/r/Y/3wGWQviIOkyLJW@p183 Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton

mm: replace vma->vm_flags direct modifications with modifier calls

2023-02-10T00:51:39+00:00

Replace direct modifications to vma->vm_flags with calls to modifier functions to be able to track flag changes and to keep vma locking correctness. [akpm@linux-foundation.org: fix drivers/misc/open-dice.c, per Hyeonggon Yoo] Link: https://lkml.kernel.org/r/20230126193752.297968-5-surenb@google.com Signed-off-by: Suren Baghdasaryan Acked-by: Michal Hocko Acked-by: Mel Gorman Acked-by: Mike Rapoport (IBM) Acked-by: Sebastian Reichel Reviewed-by: Liam R. Howlett Reviewed-by: Hyeonggon Yoo <42.hyeyoo@gmail.com> Cc: Andy Lutomirski Cc: Arjun Roy Cc: Axel Rasmussen Cc: David Hildenbrand Cc: David Howells Cc: Davidlohr Bueso Cc: David Rientjes Cc: Eric Dumazet Cc: Greg Thelen Cc: Hugh Dickins Cc: Ingo Molnar Cc: Jann Horn Cc: Joel Fernandes Cc: Johannes Weiner Cc: Kent Overstreet Cc: Laurent Dufour Cc: Lorenzo Stoakes Cc: Matthew Wilcox Cc: Minchan Kim Cc: Paul E. McKenney Cc: Peter Oskolkov Cc: Peter Xu Cc: Peter Zijlstra Cc: Punit Agrawal Cc: Sebastian Andrzej Siewior Cc: Shakeel Butt Cc: Soheil Hassas Yeganeh Cc: Song Liu Cc: Vlastimil Babka Cc: Will Deacon Signed-off-by: Andrew Morton

Merge tag 'pull-iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2022-12-13T02:29:54+00:00

Pull iov_iter updates from Al Viro: "iov_iter work; most of that is about getting rid of direction misannotations and (hopefully) preventing more of the same for the future" * tag 'pull-iov_iter' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: use less confusing names for iov_iter direction initializers iov_iter: saner checks for attempt to copy to/from iterator [xen] fix "direction" argument of iov_iter_kvec() [vhost] fix 'direction' argument of iov_iter_{init,bvec}() [target] fix iov_iter_bvec() "direction" argument [s390] memcpy_real(): WRITE is "data source", not destination... [s390] zcore: WRITE is "data source", not destination... [infiniband] READ is "data destination", not source... [fsi] WRITE is "data source", not destination... [s390] copy_oldmem_kernel() - WRITE is "data source", not destination csum_and_copy_to_iter(): handle ITER_DISCARD get rid of unlikely() on page_copy_sane() calls

use less confusing names for iov_iter direction initializers

2022-11-25T18:01:55+00:00

READ/WRITE proved to be actively confusing - the meanings are "data destination, as used with read(2)" and "data source, as used with write(2)", but people keep interpreting those as "we read data from it" and "we write data to it", i.e. exactly the wrong way. Call them ITER_DEST and ITER_SOURCE - at least that is harder to misinterpret... Signed-off-by: Al Viro