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charset="UTF-8" X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 1D8B240006 X-Rspam-User: X-Stat-Signature: k7dojmtimc4yn8yy34998of3ahr1za93 X-HE-Tag: 1790986898-719525 X-HE-Meta: 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 ULL9hvTx 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 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Right now it is assumed that the restore routine in vmemmap_remap_free() will not fail; that is, if we fail to fully optimize a folio, it is assumed that restoring the folio to its pre-HVO state is guaranteed to succeed. Although vmemmap restoration may never fail in practice, properly handle such failure cases now. This will leave folios in a partially HVOed state. In a follow-up patch, failure certainly becomes possible. In the event we end up with partially-HVOed folios, make sure to: 1. Leave the HVO page flag in place. 2. Free any unused vmemmap pages. Always pass the vmemmap_tail page to the restore routine to avoid leaking the non-optimized vmemmap pages for a partially HVOed page. Signed-off-by: James Houghton --- mm/hugetlb_vmemmap.c | 49 ++++++++++++++++++++++++++++++++++---------- 1 file changed, 38 insertions(+), 11 deletions(-) diff --git a/mm/hugetlb_vmemmap.c b/mm/hugetlb_vmemmap.c index 1a2645c382ba..90db4d069ff6 100644 --- a/mm/hugetlb_vmemmap.c +++ b/mm/hugetlb_vmemmap.c @@ -235,12 +235,15 @@ static void vmemmap_restore_pte(pte_t *pte, unsigned long addr, { struct page *src = pte_page(ptep_get(pte)), *dst; + if (WARN_ON_ONCE(!walk->vmemmap_tail)) + return; + /* - * When rolling back vmemmap_remap_free(), keep the copied head page + * When restoring a partially-HVOed page, keep the copied head page * mapping and restore only PTEs currently pointing at the shared tail * page. */ - if (walk->vmemmap_tail && walk->vmemmap_tail != src) + if (walk->vmemmap_tail != src) return; VM_WARN_ON_ONCE(PageHead((const struct page *)addr)); @@ -276,6 +279,7 @@ static int vmemmap_remap_split(unsigned long start, unsigned long end) return vmemmap_remap_range(start, end, &walk); } +#define VMEMMAP_REMAP_INCOMPLETE 1 /** * vmemmap_remap_free - remap the vmemmap virtual address range [@start, @end) * to use @vmemmap_head/tail, then free vmemmap which @@ -290,7 +294,8 @@ static int vmemmap_remap_split(unsigned long start, unsigned long end) * responsibility to free pages. * @flags: modifications to vmemmap_remap_walk flags * - * Return: %0 on success, negative error code otherwise. + * Return: %0 on success, VMEMMAP_REMAP_INCOMPLETE if the page is incompletely + * optimized, negative error code otherwise. */ static int vmemmap_remap_free(unsigned long start, unsigned long end, struct page *vmemmap_head, @@ -325,7 +330,8 @@ static int vmemmap_remap_free(unsigned long start, unsigned long end, .flags = 0, }; - vmemmap_remap_range(start, end, &walk); + if (vmemmap_remap_range(start, end, &walk)) + return VMEMMAP_REMAP_INCOMPLETE; return ret; } @@ -358,6 +364,8 @@ static int alloc_vmemmap_page_list(unsigned long start, unsigned long end, * vmemmap_remap_alloc - remap the vmemmap virtual address range [@start, end) * to the page which is from the @vmemmap_pages * respectively. + * @h: the hstate for the folio whose vmemmap is getting remapped + * @folio: the folio whose vmemmap is getting remapped * @start: start address of the vmemmap virtual address range that we want * to remap. * @end: end address of the vmemmap virtual address range that we want to @@ -366,20 +374,35 @@ static int alloc_vmemmap_page_list(unsigned long start, unsigned long end, * * Return: %0 on success, negative error code otherwise. */ -static int vmemmap_remap_alloc(unsigned long start, unsigned long end, +static int vmemmap_remap_alloc(const struct hstate *h, struct folio *folio, + unsigned long start, unsigned long end, unsigned long flags) { LIST_HEAD(vmemmap_pages); - struct vmemmap_remap_walk walk = { + struct vmemmap_remap_walk walk; + struct page *vmemmap_tail; + int ret; + + vmemmap_tail = vmemmap_shared_tail_page(h->order, folio_zone(folio)); + if (WARN_ON_ONCE(!vmemmap_tail)) + return -ENOMEM; + + if (alloc_vmemmap_page_list(start, end, &vmemmap_pages)) + return -ENOMEM; + + walk = (struct vmemmap_remap_walk) { .remap_pte = vmemmap_restore_pte, + .vmemmap_tail = vmemmap_tail, .vmemmap_pages = &vmemmap_pages, .flags = flags, }; - if (alloc_vmemmap_page_list(start, end, &vmemmap_pages)) - return -ENOMEM; + ret = vmemmap_remap_range(start, end, &walk); - return vmemmap_remap_range(start, end, &walk); + /* Not all pages may have been consumed */ + free_vmemmap_page_list(&vmemmap_pages); + + return ret; } static bool vmemmap_optimize_enabled = IS_ENABLED(CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP_DEFAULT_ON); @@ -412,7 +435,7 @@ static int __hugetlb_vmemmap_restore_folio(const struct hstate *h, * When a HugeTLB page is freed to the buddy allocator, previously * discarded vmemmap pages must be allocated and remapping. */ - ret = vmemmap_remap_alloc(vmemmap_start, vmemmap_end, flags); + ret = vmemmap_remap_alloc(h, folio, vmemmap_start, vmemmap_end, flags); if (!ret) folio_clear_hugetlb_vmemmap_optimized(folio); @@ -545,7 +568,11 @@ static int __hugetlb_vmemmap_optimize_folio(const struct hstate *h, vmemmap_head, vmemmap_tail, vmemmap_pages, flags); out: - if (ret) + /* + * If ret == VMEMMAP_REMAP_INCOMPLETE, the folio might be partially + * HVOed. Leave the HVO page folio flag in place. + */ + if (ret < 0) folio_clear_hugetlb_vmemmap_optimized(folio); return ret; -- 2.56.0.rc1.315.gc6ed9934b7-goog