On 06-01 16:03, Pratyush Yadav wrote: > On Sat, May 30 2026, Pasha Tatashin wrote: > > > Currently, the number of LUO sessions is limited by a fixed number of > > pre-allocated pages for serialization (16 pages, allowing for ~819 > > sessions). > > > > This limitation is problematic if LUO is used to support things such as > > systemd file descriptor store, and would be used not just as VM memory > > but to save other states on the machine. > > > > Remove this limit by transitioning to a linked-block approach for > > session metadata serialization. Instead of a single contiguous block, > > session metadata is now stored in a chain of 16-page blocks. Each block > > starts with a header containing the physical address of the next block > > and the number of session entries in the current block. > > > > Acked-by: Mike Rapoport (Microsoft) <[email protected]> > > Signed-off-by: Pasha Tatashin <[email protected]> > > --- > [...] > > @@ -63,13 +58,15 @@ > > #define _LINUX_KHO_ABI_LUO_H > > > > #include <linux/align.h> > > +#include <linux/kho/abi/block.h> > > #include <uapi/linux/liveupdate.h> > > > > /* > > * The LUO state is registered under this KHO entry name. > > */ > > #define LUO_KHO_ENTRY_NAME "LUO" > > -#define LUO_ABI_COMPATIBLE "luo-v3" > > +#define LUO_COMPAT_BASE "luo-v3" > > +#define LUO_ABI_COMPATIBLE LUO_COMPAT_BASE "-" KHO_BLOCK_ABI_COMPATIBLE > > That's clever :-) > > [...] > > int luo_session_serialize(void) > > { > > struct luo_session_header *sh = &luo_session_global.outgoing; > > struct luo_session *session; > > - int i = 0; > > + struct kho_block_it it; > > int err; > > > > down_write(&luo_session_serialize_rwsem); > > down_write(&sh->rwsem); > > *sh->sessions_pa = 0; > > > > + kho_block_it_init(&it, &sh->block_set); > > + > > list_for_each_entry(session, &sh->list, list) { > > - err = luo_session_freeze_one(session, &sh->ser[i]); > > - if (err) > > + struct luo_session_ser *ser = kho_block_it_next(&it); > > + > > + if (!ser) { > > + err = -ENOSPC; > > goto err_undo; > > + } > > > > - strscpy(sh->ser[i].name, session->name, > > - sizeof(sh->ser[i].name)); > > - i++; > > - } > > + err = luo_session_freeze_one(session, ser); > > + if (err) { > > + kho_block_it_prev(&it); > > + goto err_undo; > > + } > > > > - if (sh->header_ser && sh->count > 0) { > > - sh->header_ser->count = sh->count; > > - *sh->sessions_pa = virt_to_phys(sh->header_ser); > > + strscpy(ser->name, session->name, sizeof(ser->name)); > > } > > + > > + kho_block_it_finalize(&it); > > + > > + if (sh->sessions_pa && sh->count > 0) > > Nit: Why check for sh->sessions_pa? It can never be NULL.
Good point, I will remove it. > > Other than this, > > Reviewed-by: Pratyush Yadav (Google) <[email protected]> > > > + *sh->sessions_pa = sh->block_set.head_pa; > > up_write(&sh->rwsem); > > > > return 0; > > > > err_undo: > > list_for_each_entry_continue_reverse(session, &sh->list, list) { > > - i--; > > - luo_session_unfreeze_one(session, &sh->ser[i]); > > - memset(sh->ser[i].name, 0, sizeof(sh->ser[i].name)); > > + struct luo_session_ser *ser = kho_block_it_prev(&it); > > + > > + luo_session_unfreeze_one(session, ser); > > + memset(ser->name, 0, sizeof(ser->name)); > > } > > up_write(&sh->rwsem); > > up_write(&luo_session_serialize_rwsem); > > -- > Regards, > Pratyush Yadav
