Messages in this thread | | | Date | Wed, 10 Aug 2022 11:02:55 +0200 | Subject | Re: [PATCH v5] mm/page_owner.c: add llseek for page_owner | From | Vlastimil Babka <> |
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On 8/10/22 03:33, Kassey Li wrote: > > > On 8/9/2022 5:30 PM, Vlastimil Babka (SUSE) wrote: >> On 8/9/22 04:47, Kassey Li wrote: >>> There is usage to dump a given cma region page_owner >>> instead of all page's. >>> >>> This change allows to specify a ppos as start_pfn >>> by fseek. >>> >>> Any invalid ppos will be skipped, so it did not >>> broken the origin dump feature. >>> >>> Suggested-by: Vlastimil Babka <vbabka@suse.cz> >>> Signed-off-by: Kassey Li <quic_yingangl@quicinc.com> >>> --- >>> Documentation/vm/page_owner.rst | 6 ++++++ >>> mm/internal.h | 5 +++++ >>> mm/page_owner.c | 9 ++++++--- >>> 3 files changed, 17 insertions(+), 3 deletions(-) >>> >>> diff --git a/Documentation/vm/page_owner.rst b/Documentation/vm/page_owner.rst >>> index f5c954afe97c..8d33d976da8a 100644 >>> --- a/Documentation/vm/page_owner.rst >>> +++ b/Documentation/vm/page_owner.rst >>> @@ -95,6 +95,12 @@ Usage >>> PFN XXX ... >>> // Detailed stack >>> >>> + By default, it will do full pfn dump, to start with a given pfn, >>> + page_owner supports fseek. >>> + >>> + FILE *fp = fopen("/sys/kernel/debug/page_owner", "r"); >>> + fseek(fp, pfn_start, SEEK_SET); >>> + >>> The ``page_owner_sort`` tool ignores ``PFN`` rows, puts the remaining rows >>> in buf, uses regexp to extract the page order value, counts the times >>> and pages of buf, and finally sorts them according to the parameter(s). >>> diff --git a/mm/internal.h b/mm/internal.h >>> index c0f8fbe0445b..1ad8f86e6e33 100644 >>> --- a/mm/internal.h >>> +++ b/mm/internal.h >>> @@ -189,6 +189,11 @@ extern void reclaim_throttle(pg_data_t *pgdat, enum vmscan_throttle_state reason >>> */ >>> extern pmd_t *mm_find_pmd(struct mm_struct *mm, unsigned long address); >>> >>> +/* >>> + * in mm/page_owner.c: >> >> This should say where it's defined, not used from, and that's >> fs/proc/base.c. But it's already declared in fs/proc/internal.h so maybe >> page_owner.c could just include that header (although it's a bit meh). > ok, let's do it.
Sorry, my suggestion was wrong as the kernel test bot just showed us. mem_lseek() may be unavailable without CONFIG_PROC_FS. The easiest way is you add a page_owner specific one back, but make it correct for SEEK_CUR. Thanks.
>> >>> + */ >>> +extern loff_t mem_lseek(struct file *, loff_t, int); >>> + >>> /* >>> * in mm/page_alloc.c >>> */ >>> diff --git a/mm/page_owner.c b/mm/page_owner.c >>> index e4c6f3f1695b..dcbe05e206e1 100644 >>> --- a/mm/page_owner.c >>> +++ b/mm/page_owner.c >>> @@ -497,8 +497,10 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) >>> return -EINVAL; >>> >>> page = NULL; >>> - pfn = min_low_pfn + *ppos; >>> - >>> + if (*ppos == 0) >>> + pfn= min_low_pfn; >> >> missing space before '=' > > my bad, for v6 > > ./scripts/checkpatch.pl > v6-0001-mm-page_owner.c-add-llseek-for-page_owner.patch > total: 0 errors, 0 warnings, 46 lines checked > > v6-0001-mm-page_owner.c-add-llseek-for-page_owner.patch has no obvious > style problems and is ready for submission. >> >>> + else >>> + pfn = *ppos; >>> /* Find a valid PFN or the start of a MAX_ORDER_NR_PAGES area */ >>> while (!pfn_valid(pfn) && (pfn & (MAX_ORDER_NR_PAGES - 1)) != 0) >>> pfn++; >>> @@ -561,7 +563,7 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) >>> continue; >>> >>> /* Record the next PFN to read in the file offset */ >>> - *ppos = (pfn - min_low_pfn) + 1; >>> + *ppos = pfn + 1; >>> >>> return print_page_owner(buf, count, pfn, page, >>> page_owner, handle); >>> @@ -660,6 +662,7 @@ static void init_early_allocated_pages(void) >>> >>> static const struct file_operations proc_page_owner_operations = { >>> .read = read_page_owner, >>> + .llseek = mem_lseek, >>> }; >>> >>> static int __init pageowner_init(void) >>
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