From 27600805e62f800bacf990354632eae4e487d34c Mon Sep 17 00:00:00 2001 From: Yazen Ghannam Date: Thu, 3 Sep 2026 10:43:25 -0500 Subject: x86/amd_node: Fix PCI device reference counting in amd_smn_init() The local "root" pointer is a temporary variable used during the device search. Therefore, refcount related to the search iterators should be cleaned up after the search is complete. Use the __free() cleanup macro to ensure the refcount is decremented when the temporary pointer goes out of scope. Additionally, increment the refcount when caching a root pointer. This ensures the in-use refcount is separate from the temporary search refcounting. Finally, drop the redundant "root = NULL" before the second search loop. The pci_get_class() iterator always decrements the refcount of its "from" argument, so the first loop can only fall through with "root" already NULL. Fixes: 0a4b61d9c2e4 ("x86/amd_node: Fix AMD root device caching") Closes: https://sashiko.dev/#/patchset/20260806160159.230453-1-jason.andryuk%40amd.com Reported-by: Sashiko Assisted-by: LLM Signed-off-by: Yazen Ghannam Signed-off-by: Borislav Petkov (AMD) Reviewed-by: Mario Limonciello (AMD) Cc: Link: https://patch.msgid.link/20260903154325.74343-1-yazen.ghannam@amd.com --- fs/drop_caches.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 98 insertions(+) create mode 100644 fs/drop_caches.c (limited to 'fs/drop_caches.c') diff --git a/fs/drop_caches.c b/fs/drop_caches.c new file mode 100644 index 000000000..49f56a598 --- /dev/null +++ b/fs/drop_caches.c @@ -0,0 +1,98 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Implement the manual drop-all-pagecache function + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include "internal.h" + +/* A global variable is a bit ugly, but it keeps the code simple */ +static int sysctl_drop_caches; + +static void drop_pagecache_sb(struct super_block *sb, void *unused) +{ + struct inode *inode, *toput_inode = NULL; + + spin_lock(&sb->s_inode_list_lock); + list_for_each_entry(inode, &sb->s_inodes, i_sb_list) { + spin_lock(&inode->i_lock); + /* + * We must skip inodes in unusual state. We may also skip + * inodes without pages but we deliberately won't in case + * we need to reschedule to avoid softlockups. + */ + if ((inode_state_read(inode) & (I_FREEING | I_WILL_FREE | I_NEW)) || + (mapping_empty(inode->i_mapping) && !need_resched())) { + spin_unlock(&inode->i_lock); + continue; + } + __iget(inode); + spin_unlock(&inode->i_lock); + spin_unlock(&sb->s_inode_list_lock); + + invalidate_mapping_pages(inode->i_mapping, 0, -1); + iput(toput_inode); + toput_inode = inode; + + cond_resched(); + spin_lock(&sb->s_inode_list_lock); + } + spin_unlock(&sb->s_inode_list_lock); + iput(toput_inode); +} + +static int drop_caches_sysctl_handler(const struct ctl_table *table, int write, + void *buffer, size_t *length, loff_t *ppos) +{ + int ret; + + ret = proc_dointvec_minmax(table, write, buffer, length, ppos); + if (ret) + return ret; + if (write) { + static int stfu; + + if (sysctl_drop_caches & 1) { + lru_add_drain_all(); + iterate_supers(drop_pagecache_sb, NULL); + count_vm_event(DROP_PAGECACHE); + } + if (sysctl_drop_caches & 2) { + drop_slab(); + count_vm_event(DROP_SLAB); + } + if (!stfu) { + pr_info("%s (%d): drop_caches: %d\n", + current->comm, task_pid_nr(current), + sysctl_drop_caches); + } + stfu |= sysctl_drop_caches & 4; + } + return 0; +} + +static const struct ctl_table drop_caches_table[] = { + { + .procname = "drop_caches", + .data = &sysctl_drop_caches, + .maxlen = sizeof(int), + .mode = 0200, + .proc_handler = drop_caches_sysctl_handler, + .extra1 = SYSCTL_ONE, + .extra2 = SYSCTL_FOUR, + }, +}; + +static int __init init_vm_drop_caches_sysctls(void) +{ + register_sysctl_init("vm", drop_caches_table); + return 0; +} +fs_initcall(init_vm_drop_caches_sysctls); -- cgit v1.3.1