user/sven/linux.git/fs/proc, branch v6.6.75

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

2025-01-23T16:21:16Z

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/task_mmu: fix pagemap flags with PMD THP entries on 32bit

2025-01-09T12:32:08Z

commit 3754137d263f52f4b507cf9ae913f8f0497d1b0e upstream. Entries (including flags) are u64, even on 32bit. So right now we are cutting of the flags on 32bit. This way, for example the cow selftest complains about: # ./cow ... Bail Out! read and ioctl return unmatched results for populated: 0 1 Link: https://lkml.kernel.org/r/20241217195000.1734039-1-david@redhat.com Fixes: 2c1f057e5be6 ("fs/proc/task_mmu: properly detect PM_MMAP_EXCLUSIVE per page of PMD-mapped THPs") Signed-off-by: David Hildenbrand Cc: Oscar Salvador Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

fs/proc/kcore.c: Clear ret value in read_kcore_iter after successful iov_iter_zero

2024-12-09T09:33:07Z

commit 088f294609d8f8816dc316681aef2eb61982e0da upstream. If iov_iter_zero succeeds after failed copy_from_kernel_nofault, we need to reset the ret value to zero otherwise it will be returned as final return value of read_kcore_iter. This fixes objdump -d dump over /proc/kcore for me. Cc: stable@vger.kernel.org Cc: Alexander Gordeev Fixes: 3d5854d75e31 ("fs/proc/kcore.c: allow translation of physical memory addresses") Signed-off-by: Jiri Olsa Link: https://lore.kernel.org/r/20241121231118.3212000-1-jolsa@kernel.org Acked-by: Alexander Gordeev Signed-off-by: Christian Brauner Signed-off-by: Greg Kroah-Hartman

fs/proc/kcore.c: fix coccinelle reported ERROR instances

2024-12-09T09:32:18Z

[ Upstream commit 82e33f249f1126cf3c5f39a31b850d485ac33bc3 ] Coccinelle complains about the nested reuse of the pointer `iter' with different pointer type: ./fs/proc/kcore.c:515:26-30: ERROR: invalid reference to the index variable of the iterator on line 499 ./fs/proc/kcore.c:534:23-27: ERROR: invalid reference to the index variable of the iterator on line 499 ./fs/proc/kcore.c:550:40-44: ERROR: invalid reference to the index variable of the iterator on line 499 ./fs/proc/kcore.c:568:27-31: ERROR: invalid reference to the index variable of the iterator on line 499 ./fs/proc/kcore.c:581:28-32: ERROR: invalid reference to the index variable of the iterator on line 499 ./fs/proc/kcore.c:599:27-31: ERROR: invalid reference to the index variable of the iterator on line 499 ./fs/proc/kcore.c:607:38-42: ERROR: invalid reference to the index variable of the iterator on line 499 ./fs/proc/kcore.c:614:26-30: ERROR: invalid reference to the index variable of the iterator on line 499 Replacing `struct kcore_list *iter' with `struct kcore_list *tmp' doesn't change the scope and the functionality is the same and coccinelle seems happy. NOTE: There was an issue with using `struct kcore_list *pos' as the nested iterator. The build did not work! [akpm@linux-foundation.org: s/tmp/pos/] Link: https://lkml.kernel.org/r/20241029054651.86356-2-mtodorovac69@gmail.com Link: https://lore.kernel.org/all/CAHk-=wgRr_D8CB-D9Kg-c=EHreAsk5SqXPwr9Y7k9sA6cWXJ6w@mail.gmail.com/ [1] Link: https://lkml.kernel.org/r/20220331223700.902556-1-jakobkoschel@gmail.com Fixes: 04d168c6d42d ("fs/proc/kcore.c: remove check of list iterator against head past the loop body") Signed-off-by: Jakob Koschel Signed-off-by: Mirsad Todorovac Cc: Mike Rapoport Cc: David Hildenbrand Cc: Oscar Salvador Cc: "Brian Johannesmeyer" Cc: Cristiano Giuffrida Cc: "Bos, H.J." Cc: Alexey Dobriyan Cc: Andrew Morton Cc: Yang Li Cc: Baoquan He Cc: Hari Bathini Cc: Yan Zhen Cc: Alexander Gordeev Signed-off-by: Andrew Morton Signed-off-by: Sasha Levin

fs/proc: do_task_stat: use sig->stats_lock to gather the threads/children stats

2024-12-09T09:31:41Z

[ Upstream commit 7601df8031fd67310af891897ef6cc0df4209305 ] lock_task_sighand() can trigger a hard lockup. If NR_CPUS threads call do_task_stat() at the same time and the process has NR_THREADS, it will spin with irqs disabled O(NR_CPUS * NR_THREADS) time. Change do_task_stat() to use sig->stats_lock to gather the statistics outside of ->siglock protected section, in the likely case this code will run lockless. Link: https://lkml.kernel.org/r/20240123153357.GA21857@redhat.com Signed-off-by: Oleg Nesterov Signed-off-by: Dylan Hatch Cc: Eric W. Biederman Cc: Signed-off-by: Andrew Morton [ Resolve minor conflicts ] Signed-off-by: Bin Lan Signed-off-by: Sasha Levin

proc/softirqs: replace seq_printf with seq_put_decimal_ull_width

2024-12-09T09:31:39Z

[ Upstream commit 84b9749a3a704dcc824a88aa8267247c801d51e4 ] seq_printf is costy, on a system with n CPUs, reading /proc/softirqs would yield 10*n decimal values, and the extra cost parsing format string grows linearly with number of cpus. Replace seq_printf with seq_put_decimal_ull_width have significant performance improvement. On an 8CPUs system, reading /proc/softirqs show ~40% performance gain with this patch. Signed-off-by: David Wang <00107082@163.com> Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin

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

2024-11-14T12:19:39Z

commit b8ee299855f08539e04d6c1a6acb3dc9e5423c00 upstream. 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 Signed-off-by: Greg Kroah-Hartman

fs/proc/kcore.c: allow translation of physical memory addresses

2024-10-17T13:24:37Z

commit 3d5854d75e3187147613130561b58f0b06166172 upstream. When /proc/kcore is read an attempt to read the first two pages results in HW-specific page swap on s390 and another (so called prefix) pages are accessed instead. That leads to a wrong read. Allow architecture-specific translation of memory addresses using kc_xlate_dev_mem_ptr() and kc_unxlate_dev_mem_ptr() callbacks similarily to /dev/mem xlate_dev_mem_ptr() and unxlate_dev_mem_ptr() callbacks. That way an architecture can deal with specific physical memory ranges. Re-use the existing /dev/mem callback implementation on s390, which handles the described prefix pages swapping correctly. For other architectures the default callback is basically NOP. It is expected the condition (vaddr == __va(__pa(vaddr))) always holds true for KCORE_RAM memory type. Link: https://lkml.kernel.org/r/20240930122119.1651546-1-agordeev@linux.ibm.com Signed-off-by: Alexander Gordeev Suggested-by: Heiko Carstens Cc: Vasily Gorbik Cc: Signed-off-by: Andrew Morton Signed-off-by: Greg Kroah-Hartman

proc: add config & param to block forcing mem writes

2024-10-10T09:57:27Z

[ Upstream commit 41e8149c8892ed1962bd15350b3c3e6e90cba7f4 ] This adds a Kconfig option and boot param to allow removing the FOLL_FORCE flag from /proc/pid/mem write calls because it can be abused. The traditional forcing behavior is kept as default because it can break GDB and some other use cases. Previously we tried a more sophisticated approach allowing distributions to fine-tune /proc/pid/mem behavior, however that got NAK-ed by Linus [1], who prefers this simpler approach with semantics also easier to understand for users. Link: https://lore.kernel.org/lkml/CAHk-=wiGWLChxYmUA5HrT5aopZrB7_2VTa0NLZcxORgkUe5tEQ@mail.gmail.com/ [1] Cc: Doug Anderson Cc: Jeff Xu Cc: Jann Horn Cc: Kees Cook Cc: Ard Biesheuvel Cc: Christian Brauner Suggested-by: Linus Torvalds Signed-off-by: Linus Torvalds Signed-off-by: Adrian Ratiu Link: https://lore.kernel.org/r/20240802080225.89408-1-adrian.ratiu@collabora.com Signed-off-by: Christian Brauner Signed-off-by: Sasha Levin

sysctl: always initialize i_uid/i_gid

2024-08-11T10:47:13Z

[ Upstream commit 98ca62ba9e2be5863c7d069f84f7166b45a5b2f4 ] Always initialize i_uid/i_gid inside the sysfs core so set_ownership() can safely skip setting them. Commit 5ec27ec735ba ("fs/proc/proc_sysctl.c: fix the default values of i_uid/i_gid on /proc/sys inodes.") added defaults for i_uid/i_gid when set_ownership() was not implemented. It also missed adjusting net_ctl_set_ownership() to use the same default values in case the computation of a better value failed. Fixes: 5ec27ec735ba ("fs/proc/proc_sysctl.c: fix the default values of i_uid/i_gid on /proc/sys inodes.") Cc: stable@vger.kernel.org Signed-off-by: Thomas Weißschuh Signed-off-by: Joel Granados Signed-off-by: Sasha Levin