mm_account_fault(9)

💅 mm_account_fault(9) — like, the page fault accounting girlies 💅

okay so this is a page from the Kernel API Manual, bestie — it's mm_account_fault(9) and it's genuinely the moment where the kernel sits down and does its page fault bookkeeping. pull up a chair 🎀

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✨ NAME ✨

mm_account_fault — do page fault accounting 💖 (yes that's the whole vibe, it literally just tallies up faults)

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🦋 SYNOPSIS 🦋

void mm_account_fault (struct mm_struct *mm , struct pt_regs *regs ,
unsigned long address , unsigned int flags , vm_fault_t ret );

it returns void, so no return value drama — it just does the thing and dips ✌️

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🌸 ARGUMENTS 🌸

• mm — the mm we're pulling the memcg out of. it can be NULL, no cap, that's allowed 🫶
• regs — the pt_regs struct pointer. when it's set to NULL we skip the accounting of perf event counters — but we still do the per-task accounting to the task that triggered this page fault. so like, don't think you're getting out of it entirely 😭
• address — the faulted address. the address that faulted. the one and only 📍
• flags — the fault flags 🚩
• ret — the fault retcode ⭐

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👑 DESCRIPTION 👑

okay so the way that this is doing the most — it takes care of most of the page fault accounting. iconic. and it also includes the PERF_COUNT_SW_PAGE_FAULTS_[MAJ|MIN] perf counter updates 🔥

but listen, bestie — the handling of PERF_COUNT_SW_PAGE_FAULTS should still be in per-arch page fault handlers at the entry of page fault. that one's not on this function, mmkay? don't come for her 💅

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🧚 SEE ALSO 🧚

Kernel file ./mm/memory.c — and like, the whole extended friend group:

• free_pgd_range(9), free_pgtables(9), __vm_normal_page(9), vm_normal_page(9), vm_normal_folio(9)
• vm_normal_page_pmd(9), vm_normal_folio_pmd(9), vm_normal_page_pud(9)
• restore_exclusive_pte(9), cond_install_uffd_wp_ptes(9)
• zap_vma_for_reaping(9), unmap_vmas(9), zap_vma_range_batched(9), zap_vma_range(9), zap_special_vma_range(9)
• vm_insert_pages(9), vm_insert_page(9), vm_map_pages(9), vm_map_pages_zero(9)
• vmf_insert_pfn_prot(9), vmf_insert_pfn(9), remap_pfn_range(9), vm_iomap_memory(9)
• __vmf_anon_prepare(9), finish_mkwrite_fault(9)
• unmap_mapping_folio(9), unmap_mapping_pages(9), unmap_mapping_range(9)
• set_pte_range(9), finish_fault(9)
• follow_pfnmap_start(9), follow_pfnmap_end(9)
• generic_access_phys(9), access_remote_vm(9), copy_remote_vm_str(9), folio_zero_user(9)

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and that's the whole page, bestie — go account some faults responsibly 💜

this cutie came out of ./mm and it's dated October 2026, iykyk 🎀✨