| Message ID | 20220808073606.29666-1-quic_yingangl@quicinc.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [v4] mm/page_owner.c: add llseek for page_owner | expand |
On 8/8/22 09:36, 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 (SUSE) <vbabka@kernel.org> Thanks, but please change it to Vlastimil Babka <vbabka@suse.cz> It was some mistake between me and thunderbird that it was sent from @k.o. > Signed-off-by: Kassey Li <quic_yingangl@quicinc.com> > --- > mm/page_owner.c | 20 ++++++++++++++++++-- > 1 file changed, 18 insertions(+), 2 deletions(-) > > diff --git a/mm/page_owner.c b/mm/page_owner.c > index e4c6f3f1695b..231b1877af99 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -497,8 +497,8 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) > return -EINVAL; > > page = NULL; > - pfn = min_low_pfn + *ppos; > > + pfn = *ppos; Maybe we could still optimize the typical case a bit such that when it's 0, we skip to min_low_pfn immediately. > /* 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 +561,7 @@ 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); > @@ -570,6 +570,21 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) > return 0; > } > > +static loff_t llseek_page_owner(struct file *file, loff_t offset, int whence) > +{ > + loff_t retval = 0; > + switch (whence) { > + case SEEK_CUR: It's not correct for SEEK_CUR to behave like this, no? Can we perhaps reuse the existing mem_lseek() ? Also we should update Documentation/mm/page_owner.rst to document the lseek support and that it works with a pfn. Thanks! > + case SEEK_SET: > + file->f_pos = offset; > + break; > + default: > + retval = -ENXIO; > + } > + > + return retval; > +} > + > static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone) > { > unsigned long pfn = zone->zone_start_pfn; > @@ -660,6 +675,7 @@ static void init_early_allocated_pages(void) > > static const struct file_operations proc_page_owner_operations = { > .read = read_page_owner, > + .llseek = llseek_page_owner, > }; > > static int __init pageowner_init(void)
On 8/8/2022 11:33 PM, Vlastimil Babka (SUSE) wrote: > On 8/8/22 09:36, 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 (SUSE) <vbabka@kernel.org> > > Thanks, but please change it to Vlastimil Babka <vbabka@suse.cz> > It was some mistake between me and thunderbird that it was sent from @k.o. Ok, will change it. > >> Signed-off-by: Kassey Li <quic_yingangl@quicinc.com> >> --- >> mm/page_owner.c | 20 ++++++++++++++++++-- >> 1 file changed, 18 insertions(+), 2 deletions(-) >> >> diff --git a/mm/page_owner.c b/mm/page_owner.c >> index e4c6f3f1695b..231b1877af99 100644 >> --- a/mm/page_owner.c >> +++ b/mm/page_owner.c >> @@ -497,8 +497,8 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) >> return -EINVAL; >> >> page = NULL; >> - pfn = min_low_pfn + *ppos; >> >> + pfn = *ppos; > > Maybe we could still optimize the typical case a bit such that when it's 0, > we skip to min_low_pfn immediately. > >> /* 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 +561,7 @@ 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); >> @@ -570,6 +570,21 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) >> return 0; >> } >> >> +static loff_t llseek_page_owner(struct file *file, loff_t offset, int whence) >> +{ >> + loff_t retval = 0; >> + switch (whence) { >> + case SEEK_CUR: > > It's not correct for SEEK_CUR to behave like this, no? > Can we perhaps reuse the existing mem_lseek() ? agree. > > Also we should update Documentation/mm/page_owner.rst to document the lseek > support and that it works with a pfn. will do this in v5 patch set. > > Thanks! > >> + case SEEK_SET: >> + file->f_pos = offset; >> + break; >> + default: >> + retval = -ENXIO; >> + } >> + >> + return retval; >> +} >> + >> static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone) >> { >> unsigned long pfn = zone->zone_start_pfn; >> @@ -660,6 +675,7 @@ static void init_early_allocated_pages(void) >> >> static const struct file_operations proc_page_owner_operations = { >> .read = read_page_owner, >> + .llseek = llseek_page_owner, >> }; >> >> static int __init pageowner_init(void) >
diff --git a/mm/page_owner.c b/mm/page_owner.c index e4c6f3f1695b..231b1877af99 100644 --- a/mm/page_owner.c +++ b/mm/page_owner.c @@ -497,8 +497,8 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) return -EINVAL; page = NULL; - pfn = min_low_pfn + *ppos; + 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 +561,7 @@ 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); @@ -570,6 +570,21 @@ read_page_owner(struct file *file, char __user *buf, size_t count, loff_t *ppos) return 0; } +static loff_t llseek_page_owner(struct file *file, loff_t offset, int whence) +{ + loff_t retval = 0; + switch (whence) { + case SEEK_CUR: + case SEEK_SET: + file->f_pos = offset; + break; + default: + retval = -ENXIO; + } + + return retval; +} + static void init_pages_in_zone(pg_data_t *pgdat, struct zone *zone) { unsigned long pfn = zone->zone_start_pfn; @@ -660,6 +675,7 @@ static void init_early_allocated_pages(void) static const struct file_operations proc_page_owner_operations = { .read = read_page_owner, + .llseek = llseek_page_owner, }; static int __init pageowner_init(void)
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 (SUSE) <vbabka@kernel.org> Signed-off-by: Kassey Li <quic_yingangl@quicinc.com> --- mm/page_owner.c | 20 ++++++++++++++++++-- 1 file changed, 18 insertions(+), 2 deletions(-)